New research suggests that many more people have had the coronavirus without any symptoms, fueling the hope that it will prove to be much less deadly than originally feared.
Based on known cases, health officials have said that the virus usually causes mild or moderate flu disease.
There is growing evidence that a significant number of people may have no symptoms.
Icelandic scientists examined 6% of its population to see how many of them had previously undetected infections and found that around 0.7% were positive.
Coronavirus around the world
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JAKARTA, INDONESIA – April 18, 2020: An officer walks past a pit for coronavirus victims in the city of Jakarta.- PHOTOGRAPHY OF Soleh / Opn Images / Barcroft Studios / Future Publishing (photo credit should read Soleh / Opn Images / Barcroft Media via Getty Images)
Belgian doctor Antoine Sassine, urologist at Chirec Delta hospital, who survived coronavirus disease (COVID-19) after 6 weeks in the intensive care unit and 3.5 weeks in a coma embraces his wife Alexandra then that he leaves the hospital in Brussels, Belgium, April 19, 2020. REUTERS / Yves Herman IMAGES TPX DU JOUR
President Donald Trump speaks during a briefing of the Coronavirus task force at the White House on Sunday April 19, 2020 in Washington. (Photo AP / Patrick Semansky)
OLYMPIA, WA – April 19: Hundreds of people gather to protest the state home order at the Capitol on April 19, 2020 in Olympia, Washington. Washington State Governor Jay Inslee instituted the order last month to slow the spread of the coronavirus (COVID-19). (Photo by Karen Ducey / Getty Images)
Doug Hassebroek picks up balloons for his son Felix’s birthday party during the coronavirus disease (COVID-19) epidemic in Brooklyn, New York, United States, April 18, 2020. REUTERS / Caitlin Ochs TPX IMAGES OF THE DAY
Workers make coffins at the workshop of a funeral home business during a government-imposed national foreclosure against COVID-19 coronavirus in Secunderabad, twin city of Hyderabad, on 20 April 2020 (photo by NOAH SEELAM / AFP) (Photo by NOAH SEELAM / AFP via Getty Images)
TOPSHOT – Novice monks wearing face shields to prevent the spread of the COVID-19 coronavirus attend religious studies at the Wat Molilokkayaram Buddhist temple in Bangkok on April 20, 2020. (Photo by Lillian SUWANRUMPHA / AFP) (photo by LILLIAN SUWANRUMPHA / AFP via Getty Images)
NEW YORK, April 19, 2020. A patient is driven to an ambulance at Coney Island Hospital in the Brooklyn neighborhood of New York, United States, on April 19, 2020. The total number of COVID-19 cases in the United States has exceeded 750,000 Sunday evening, reaching 759,086 at 8:00 p.m., 0000 GMT Monday, according to the Center for Systems Science and Engineering, CSSE, at Johns Hopkins University.
A total of 40,661 people have died from the disease in the country, according to the CSSE. (Photo by Michael Nagle / Xinhua via Getty) (Xinhua / via Getty Images)
OLYMPIA, WA – April 19: A woman disguised as a statue of liberty walks with her dog as hundreds of people gather to protest the order to stay home April 19, 2020 in Olympia, Washington. Governor Jay Inslee issued the order last month to slow the spread of the coronoavirus (COVID-19). The Washington state patrol was there to enforce the guidelines on social estrangement and the banning of major events, but said it would not impose the right of free speech on peoples. (Photo by Karen Ducey / Getty Images)
OLYMPIA, WA – April 19: Hundreds of people gather to protest the order to stay home April 19, 2020 in Olympia, Washington. Governor Jay Inslee issued the order last month to slow the spread of the coronoavirus (COVID-19). The Washington state patrol was there to enforce the guidelines on social estrangement and the banning of major events, but said it would not impose the right of free speech on peoples. (Photo by Karen Ducey / Getty Images)
KABUL, AFGHANISTASN – April 19: A man wearing a mask is seen at the Darul Aman Palace which is used as a temporary healthcare facility for COVID-19 patients in Kabul, Afghanistan on April 19, 2020. Afghanistan on Saturday became the iconic 19th century Darul Aman Palace in Kabul in an isolation facility with 200 beds for patients with coronavirus. (Photo by Haroon Sabawoon / Anadolu Agency via Getty Images)
A local Gaddi shepherd sits with his flock in a temporary shelter against the backdrop of the snow-capped Himalayan Dhauladhar range in Dharmsala, Himachal Pradesh, India, Sunday, April 19, 2020. The Gaddis, who remain mobile most of the years, taking their herds in green pastures, receive special passes to move during the state foreclosure. (Photo AP / Ashwini Bhatia)
Bas, a vendor in a converted glacier, waits for customers for his FFP2 masks, selling for 9 euros a piece, or 3 for 25 euros, as protection against coronavirus in Amsterdam, The Netherlands, Sunday, April 19, 2020. (Photo AP / Peter Dejong)
People throw daffodils in Warsaw, Poland on Sunday, April 19, 2020 in memory of the fighters at the anniversary ceremony of the unfortunate struggle for the 1943 Warsaw Ghetto Uprising. Observances have been reduced and no crowds was present due to the spread of the new coronavirus and the demands of social distancing. (Photo AP / Czarek Sokolowski)
Ecumenical Patriarch Bartholomew I, spiritual leader of the world’s Orthodox Christians, leads the Easter service at the Patriarchal Church of St. George in Istanbul on Sunday, April 19, 2020, with no worshipers present, to help contain the spread of the coronavirus. For Orthodox Christians, it is normally a time of reflection and joy, of centenary ceremonies imbued with symbolism and tradition, but this year, Easter, by far the most important religious holiday for the 300 million Orthodox of world, was basically canceled. in a world locked by the COVID-19 pandemic. (Photo Ozan Kose / Pool via AP)
Children, some wearing protective masks to prevent the spread of the coronavirus, play baseball on a footbridge leading to the Shibuya Hikawa-Jijja Shinto shrine, Sunday, April 19, 2020, in Tokyo. (Photo AP / Kiichiro Sato)
Faithful wearing masks to protect themselves from the coronavirus, attend the Orthodox Christian Easter service in a church in Zenica, central Bosnia, on Sunday, April 19, 2020. (AP Photo / Almir Alic)
Visitors wearing face masks to help protect themselves from the spread of the new coronavirus are walking along the Han River in a park in Seoul, South Korea, Sunday April 19, 2020. The Prime Minister of South Korea said that the countries would maintain much of its social distancing guidelines until May 5, but will relax some limits. (AP Photo / Lee Jin-man)
A man walks past the Twin Towers during the motion control order issued to help curb the outbreak of coronavirus disease in Kuala Lumpur, Malaysia, Sunday, April 19, 2020. The Malaysian government has issued a restricted traffic order for public viewing until April 28 to help curb the spread of the new coronavirus. (Photo AP / Vincent Thian)
Pedestrians cross Battery Park on Saturday April 18, 2020, in the Manhattan district of New York. (Photo AP / Frank Franklin II)
Boy wearing face mask carries small bowl of githeri, or mixed beans and corn, to eat for him as he walks past an informative wall mural warning people of the risk of the new coronavirus, painted by Mathare Roots graffiti artists group of young people in the slum of Mathare, or informal settlement, in Nairobi, Kenya Saturday April 18, 2020. Africa now has more than 1,000 deaths from COVID-19, African Centers for Control and Prevention said on Saturday diseases, with 52 of the continent’s 54 countries reporting cases. (AP Photo / Brian Inganga)
Passengers, left, who have just arrived at the airport, pass South African Airways crew, on the right, on their way to security at Frankfurt Airport, Germany, Saturday, 18 April 2020. Due to the new coronavirus epidemic about 95% of the flights have been canceled. (AP Photo / Michael Probst)
People wait in a queue as a volunteer carries food for distribution during the isolation in New Delhi, India on Saturday April 18, 2020. Indian Prime Minister Narendra Modi extended the largest confinement on Tuesday to prevent the peak of the epidemic, with officials racing to make up for lost time. (AP Photo / Manish Swarup)
A Lithuanian Orthodox priest and believers pray during the blessing ceremony for Easter cakes and eggs at the Orthodox Church of the Holy Spirit in Vilnius, Lithuania, Saturday April 18, 2020. For Orthodox Christians, it is normally a time for reflection, for common mourning and joyful liberation, for secular ceremonies imbued with symbolism and tradition. But this year, Easter – by far the most important religious holiday for some 300 million Orthodox people in the world – was largely canceled due to the coronavirus pandemic. (Photo AP / Mindaugas Kulbis)
A member of the Orthodox clergy holds the sacred fire to be transferred to the predominantly Orthodox countries of the Church of the Holy Sepulcher, traditionally considered by many Christians as the site of the crucifixion and burial of Jesus Christ, in the old city of Jerusalem after the call of the traditional sacred fire ceremony off the coronaviruses, Saturday April 18, 2020. Some clerics marked the sacred fire ceremony on Saturday as the coronavirus pandemic prevented thousands of Orthodox Christians from participate in one of their oldest and most mysterious rituals at the Jerusalem church marking the site of Jesus’ grave. (Photo AP / Ariel Schalit)
Armenian clerics walk towards the Church of the Holy Sepulcher, traditionally regarded by many Christians as the site of the crucifixion and burial of Jesus Christ, in the old city of Jerusalem after the traditional sacred fire ceremony was canceled amidst the coronaviruses, Saturday April 18, 2020. Some clergy marked the sacred fire ceremony on Saturday as the coronavirus pandemic prevented thousands of Orthodox Christians from participating in one of their oldest rituals and mysterious at the Jerusalem church marking the site of the tomb of Jesus (AP Photo / Ariel Schalit)
Marisa Manzano watches workers repair the tombstone in the niche of her 88-year-old uncle who died of a coronavirus at the Poble Nou cemetery in Barcelona, Spain, Saturday April 18, 2020. (AP Photo / Emilio Morenatti)
People wearing face masks to protect themselves from contracting the COVID-19 coronavirus while crossing a street in Hong Kong, Saturday April 18, 2020. (AP Photo / Kin Cheung)
People walk at night on a quiet street in the Bronx district of New York on Friday, April 17, 2020, during the coronavirus pandemic. Governor Andrew Cuomo has issued a new executive order ordering all New Yorkers to wear masks or face covers in public when social distance does not allow them to stay six feet apart. (AP Photo / Mark Lennihan)
Catholic and tax adviser Gertrud Schop, on the right, lights candles forming a giant cross in memory of the victims of coronavirus in Germany in Zella-Mehlis, in the center of Germany, Friday April 17, 2020. Schop and the volunteers have lit nearly 4,000 candles, which lasted seven hours. Completed. (Photo AP / Jens Meyer)
NOVOSIBIRSK, RUSSIA – April 17, 2020: A Russian Orthodox priest blesses Easter cakes in an Auchan hypermarket two days before Easter. Since March 31, 2020, the Novosibirsk region has been blocked to prevent the spread of the new coronavirus disease (COVID-19). A working group of the Moscow Patriarchate has recommended praying at home during Holy Week and Easter until the lifting of the authorities-imposed closure of the coronavirus. The working group also highlighted security measures, which must be observed in areas where the epidemiological situation allows believers to go to church. As of April 17, 2020, the Novosibirsk region (including Novosibirsk) had reported more than 60 confirmed cases of the new coronavirus infection. Kirill Kukhmar / TASS (Photo by Kirill Kukhmar TASS via Getty Images)
CHUNCHEON, SOUTH KOREA – APRIL 17: Employees work on the production line for the Ichroma Covid-19 Ab test kit used to diagnose the coronavirus (COVID-19) at Boditech Med Inc. headquarters on April 17, 2020 in Chuncheon, South Korea . South Korea has called for increased public participation in social displacement, as the country witnesses a wave of community spread and imported infections leading to a resurgence of new cases of COVID-19. Coronavirus cases in South Korea hovered around 20 for the fourth day in a row, but health officials remain vigilant on cluster infections, as well as new cases from abroad. According to the Korean Center for Disease Control and Prevention, 22 new cases have been reported. The total number of infections in the country is 10,635. (Photo by Chung Sung-Jun / Getty Images)
Family member, wearing a face mask as a preventive measure against the spread of the new COVID-19 coronavirus, awaits the release of his parent from Insein prison in Yangon on April 17, 2020, as part of an annual amnesty thousands of prisoners to mark their New Year’s party in April. – More than a quarter of Myanmar’s prison population is to be released, the president’s office announced on April 17, as calls are mounting to ease pressure on overcrowded prisons and fears of coronavirus seizing the country. (Photo by Sai Aung MAIN / AFP) (Photo by SAI AUNG MAIN / AFP via Getty Images)
ISTANBUL, TURKEY – APRIL 16: Havahan Karadeniz, 107, recovered from coronavirus disease (COVID-19) after his week-long treatment at Istanbul Education Research Hospital, speaks at ” an exclusive interview with the Anadolu agency in Istanbul in Turkey on April 16, 2020. (Photo by Esra Bilgin / Anadolu Agency via Getty Images)
MELBOURNE, AUSTRALIA – APRIL 17: The Royal Arcade, usually occupied with buyers is empty due to COVID 19 on April 17, 2020 in Melbourne, Australia. (Photo by Speed Media / Icon Sportswire via Getty Images)
Medical workers wearing protective equipment in a car checking for commuters with symptoms of COVID-19 in Guarulhos, on the outskirts of Sao Paulo, Brazil, Monday, March 30, 2020. President Jair Bolsonaro remained loyal to his thesis that the concern over the new coronavirus is exaggerated and accused the Brazilian media of trying to stir up national hysteria. (Photo AP / Andre Penner)
A worker makes a coffin in Jakarta, Indonesia, Tuesday, April 14, 2020. Constrained by the coronavirus pandemic, leaders in Southeast Asia videotaped Tuesday to develop a strategy to overcome a crisis that has threatened their economies and linked millions of people to their homes under lockdowns. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially the elderly and people with existing health conditions, it can cause more serious illness or death. (Photo AP / Achmad Ibrahim)
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, talks about the coronavirus in the James Brady Press Room at the White House on Monday April 13, 2020 in Washington. (AP Photo / Alex Brandon)
GUAYAQUIL, ECUADOR – APRIL 10: Cardboard coffins with bodies await outside the Jardines de Esperanza cemetery in Guayaquil, to be buried on April 10, 2020 in Pascuales, Guayaquil, Ecuador. The province of Guayas and its capital Guayaquil are the epicenter of the COVID-19 pandemic in Ecuador, the most affected per capita country in South America. Morgues and hospitals are overcrowded and the government has started burials in mass graves in the districts of Pascuales and La Aurora. The death toll is expected to be much higher as most of the victims have not been tested or diagnosed. (Photo by Getty Images / Eduardo Maquilon / Getty Images)
Hashim, a vital worker in the healthcare industry, greets his daughter by the closed door as he maintains social distance from his family as he works amid the epidemic of coronavirus disease (COVID- 19) in New Rochelle, New York, United States, April 11. 2020. Photo taken on April 11, 2020. REUTERS / Joy Malone TPX IMAGES OF THE DAY REFILE – CORRECTING STATE
People wear body protectors with built-in masks made by a woman who sewed masks during an interlock to prevent the spread of coronavirus disease (COVID-19), in Gdynia, Poland, April 9, 2020. Photo taken on April 9, 2020. REUTERS / Jadwiga Figula
People living near the traditional medicine market wait to receive food baskets from private donors, Monday, April 13, 2020 in downtown Johannesburg. Due to the lockdown imposed by South Africa to contain the spread of COVID-19, many are unable to work. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially the elderly and people with existing health conditions, it can cause more serious illness or death (AP Photo / Jerome Delay ).
A Buddhist monk prays behind plastic sheets to help curb the spread of the coronavirus during the Thai New Year at Samian Nari Temple on Monday April 13, 2020, in Bangkok, Thailand. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially the elderly and people with existing health conditions, it can cause more serious illness or death. (Photo AP / Sakchai Lalit)
A doctor checks the temperature of a girl in Dharavi, one of the largest slums in Asia, during the lockout to prevent the spread of the new coronavirus in Mumbai, India, Monday, April 13, 2020. The new coronavirus causes Mild or moderate symptoms for most people, but for some, especially the elderly and people with existing health conditions, this can lead to more serious illness or death. (Photo AP / Rafiq Maqbool)
People wearing protective masks stand under cherry blossoms in a park on Easter Sunday during the coronavirus disease epidemic (COVID-19), in the Treptow district of Berlin, Germany, April 12, 2020 REUTERS / Michele Tantussi TPX PICTURES OF THE DAY
Un adorador judío está de pie en una azotea con vistas al Muro de las Lamentaciones mientras tiene lugar la bendición sacerdotal con un tamaño reducido, una oración tradicional que suele atraer a miles de adoradores en la fiesta de la Pascua que tiene lugar en elugar en medio del brote de la enfermedad coronavirus (COVID-19), in the Ciudad Vieja de Jerusalén el 12 de abril de 2020
US Air Force Airmen aboard a C-17 Globemaster III aircraft begin to disinfect and decontaminate the aircraft after discharging three US government contractors who tested positive for coronavirus disease in Afghanistan (COVID) -19) during the very first operational use of System Transport Isolation at Ramstein Air Base, Germany, April 10, 2020. Photo taken on April 10, 2020. US Air Force / Staff Sgt. Devin Nothstine / Document via REUTERS. THIS IMAGE HAS BEEN PROVIDED BY A THIRD PARTY.
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U.S. Air Force personnel wear coronavirus disease masks (COVID-19) during basic military graduation at 321st Training Squadron Airmen Training Complex on Joint Base San Antonio-Lackland, Texas, United States, April 9, 2020. Photo taken on April 9, 2020. USAF / Johnny Saldivar / Document to be distributed via REUTERS. THIS IMAGE HAS BEEN PROVIDED BY A THIRD PARTY.
A woman participates from her window as Easter Sunday mass is conducted from the roof of the Santa Maria della Salute church, while Italy remains stuck trying to contain the spread of coronavirus disease (COVID-19 ), Naples, Italy, April 12, 2020. REUTERS / Ciro De Luca
A policeman wearing a coronavirus helmet holds signs with others during a procession to raise public awareness of the COVID-19 coronavirus during a national lockdown imposed by the government as a preventive measure against the COVID-19 coronavirus, in Chennai on April 12, 2020. (Photo by Arun SANKAR / AFP) (Photo by ARUN SANKAR / AFP via Getty Images)
VATICAN CITY, VATICAN, APRIL 10: Pope Francis presides over the torchlight procession of Via Crucis (Way of the Cross) to commemorate the crucifixion of Jesus Christ, in St. Peter’s Square in the Vatican, Good Friday April 10, 2020 The lock was aimed at In contrast, the epidemic of Covid-19 forced the Vatican to reorganize the celebrations marking Holy Week preceding Easter. The torchlight procession of the Way of the Cross, usually celebrated at the Coliseum in Rome with a large participation of the faithful, was moved to an empty St. Peter’s square. (Photo by Riccardo De Luca / Anadolu Agency via Getty Images)
WELLINGTON, NEW ZEALAND – APRIL 11: A message to essential services workers is posted on an electronic billboard above the Wellington Expressway on April 11, 2020 in Wellington, New Zealand. New Zealand has been completely blocked since Thursday March 26 to stop the spread of COVID-19 across the country. Under COVID-19 alert level restrictions, New Zealanders are not allowed to leave their homes, except to exercise in their area or to obtain essential supplies. Offices, schools and daycare centers have been closed, as have bars, restaurants, cinemas and playgrounds. Essential services remain open, including supermarkets and pharmacies. Lockdowns are expected to remain in place for at least four weeks, with Prime Minister Jacinda Ardern warning New Zealanders of zero tolerance for those unaware of the restrictions, police being able to enforce them if necessary. (Photo by Hagen Hopkins / Getty Images)
MOSCOW REGION, RUSSIA – April 11, 2020: Medical workers in protective coveralls meet passengers on an Aeroflot charter flight for Russian evacuees from Phuket at Sheremetyevo International Airport. On March 27, the Russian government ordered a ban on international flights due to the ongoing COVID-19 pandemic, with the exception of charter flights to evacuate Russian citizens from abroad. Sergei Bobylev / TASS (Photo by Sergei Bobylev TASS via Getty Images)
ISTANBUL, TURKEY – APRIL 11: A baker prepares breads for distribution to homes after the Turkish Interior Ministry announced a 48-hour curfew in Turkey on April 11, 2020. Turkey has imposed a curfew 48 hours in 31 provinces from midnight. measures to stem the spread of the new coronavirus (COVID-19) on Friday. Bakeries, hospitals, pharmacies and workplaces producing health products and medical supplies would continue to operate. (Photo by Arif Hudaverdi Yaman / Anadolu Agency via Getty Images)
Police personnel distribute food to people in need during a government-imposed national lockdown as a preventive measure against the COVID-19 coronavirus, on the outskirts of Amritsar on April 9, 2020. (Photo by NARINDER NANU / AFP) (photo by NARINDER NANU / AFP via Getty Images)
Residents watch music group formed by Sri Lankan Navy personnel as they play outside a housing complex during a government-imposed national foreclosure as a preventative measure against coronavirus COVID-19, in Colombo on April 9, 2020 (photo by ISHARA S. KODIKARA / AFP) (Photo by ISHARA S. KODIKARA / AFP via Getty Images)
This photo taken on April 9, 2020 shows a deserted mobile staircase at the Auber RER suburban train station in Paris on the 24th day of a stop in France to curb the spread of COVID-19 disease caused by a new coronavirus. (Photo by STEPHANE DE SAKUTIN / AFP) (Photo by STEPHANE DE SAKUTIN / AFP via Getty Images)
WEST SUMATRA, INDONESIA – APRIL 9, 2020: A resident who was declared cured of the coronavirus (middle) accompanied by two nurses was released from a hospital in the city of Padang. The number of patients who tested positive for Covid-19 in Indonesia cumulatively reached 3,293 people. Of this number, 280 people died and 252 patients were declared cured. – PHOTOGRAPH BY Desrian Eristha / Opn Images / Barcroft Studios / Future Publishing (Photo credit should read Desrian Eristha / Opn Images / Barcroft Media via Getty Images)
Easter eggs are displayed in a delicatessen in Rome on April 9, 2020 when the country is closed to curb the spread of COVID-19 infection caused by the new coronavirus. (Photo by Tiziana FABI / AFP) (Photo by TIZIANA FABI / AFP via Getty Images)
A Belgian firefighter wearing full protective gear brings an ambulance to headquarters after transferring a patient infected with the new COVID-19 coronavirus to Brussels hospital, on April 09, 2020. (Photo by Aris Oikonomou / AFP) (Photo by ARIS OIKONOMOU / AFP via Getty Images)
A postman delivers mail at an empty shopping center in central Munich, southern Germany, on April 9, 2020, as public life in Bavaria is limited due to the coronavirus COVID-19. (Photo by Christof STACHE / AFP) (Photo by CHRISTOF STACHE / AFP via Getty Images)
Stores are closed on April 9, 2020 in a dessert corridor of the Gare de Lyon metro and the Paris suburban train station on the 24th day of a closure in France aimed at curbing the spread of the COVID-19 disease caused by a new coronavirus. (Photo by STEPHANE DE SAKUTIN / AFP) (Photo by STEPHANE DE SAKUTIN / AFP via Getty Images)
A health worker wearing protective overalls prepares to enter two buildings in Kuala Lumpur on April 8, 2020, after having been cordoned off due to a number of cases of individuals with a new COVID-19 coronavirus in the locals, the residents. (Photo by Mohd RASFAN / AFP) (Photo by MOHD RASFAN / AFP via Getty Images)
Jilin Province medical personnel tear apart at a ceremony before leaving as Tianhe Airport reopens in Wuhan in central Hubei Province of China April 8, 2020. – Thousands of Chinese travelers are rushed to leave Wuhan, ravaged by the COVID-19 coronavirus on April 8, as authorities lifted a travel ban of more than two months for the city where the global pandemic first appeared. (Photo by Hector RETAMAL / AFP) (Photo by HECTOR RETAMAL / AFP via Getty Images)
08 April 2020, North Rhine-Westphalia, Cologne: a man jogs in the morning in the Rheinauhafen. To contain the coronavirus, NRW has prohibited the accumulation of three or more people in public. Photo: Oliver Berg / dpa (Photo by Oliver Berg / photo alliance via Getty Images)
People, wearing face masks as a preventive measure against the spread of the new COVID-19 coronavirus, are waiting to renew their visas at the Government Immigration Center in Bangkok on April 8, 2020. (Photo by Lillian SUWANRUMPHA / AFP) (Photo by LILLIAN SUWANRUMPHA / AFP via Getty Images)
OSAKA, JAPAN – APRIL 08: A businessman wears a face mask as he walks through the front door of the nearly empty station, usually occupied by passengers on April 8, 2020 in Osaka, Japan. Prime Minister Shinzo Abe declared a state of emergency yesterday that will cover 7 of Japan’s 47 prefectures, including Tokyo and Osaka, as the Covid-19 coronavirus epidemic continues to spread across the country. The move will allow affected prefectures to take action, including the expropriation of land and private buildings and the requisition of medical supplies and food from businesses that refuse to sell them. Tokyo a enregistré 80 nouvelles infections mardi, portant le nombre total dans la capitale à 1196, avec 85 décès dans le pays. (Photo de Buddhika Weerasinghe / Getty Images)
Élève de l’école publique NSW de deuxième année, accomplissant ses devoirs quotidiens pendant l’enseignement à domicile le 07 avril 2020 à Sydney, en Australie. Alors que les restrictions COVID-19 continuent, les écoles se dirigent vers l’apprentissage en ligne via le portail étudiant NSW dédié. Le département de l’éducation de la Nouvelle-Galles du Sud a mis en place un hub en ligne d’apprentissage à partir du portail domestique où les élèves, les enseignants et les parents peuvent accéder au matériel d’apprentissage. Les écoles préparent des modules de travail depuis plusieurs jours pour garantir l’accès à l’apprentissage en ligne, à travers une gamme de plateformes technologiques. (Photo par Izhar Khan / NurPhoto via Getty Images)
Une femme portant un masque facial face à la propagation du coronavirus COVID-19 passe devant un graffiti d’ailes à Tokyo le 7 avril 2020. – Le 7 avril, le Premier ministre japonais Shinzo Abe déclarera l’état d’urgence dans certaines parties du pays , y compris Tokyo, au cours d’un pic d’infections à coronavirus. (Photo de Behrouz MEHRI / AFP) (Photo de BEHROUZ MEHRI / AFP via Getty Images)
Le ministre des Affaires étrangères Dominic Raab, qui prend en charge la réponse du gouvernement à la crise des coronavirus après que le Premier ministre Boris Johnson a été admis aux soins intensifs lundi, arrive au 10 Downing Street, à Londres. (Photo par Stefan Rousseau / PA Images via Getty Images)
Un médecin portant une combinaison de protection prélève un écouvillon sur une femme en quarantaine à domicile pour tester la maladie à coronavirus (COVID-19), dans un quartier d’Ahmedabad, en Inde, le 7 avril 2020. REUTERS / Amit Dave
Une jeune fille et son grand-père portant des masques faciaux, au milieu des préoccupations du coronavirus COVID-19, jouent dans un parc du district de Muzha à Taipei le 6 avril 2020. (Photo de Sam Yeh / AFP) (Photo de SAM YEH / AFP via Getty Images)
Des agents de santé portant des vêtements de protection sont vus devant le City One Condominium à Kuala Lumpur le 6 avril 2020, après qu’il a été bouclé en raison d’un certain nombre de cas d’individus atteints du nouveau coronavirus COVID-19 dans les locaux. (Photo de Mohd RASFAN / AFP) (Photo de MOHD RASFAN / AFP via Getty Images)
BANJUL, GAMBIE – 04 AVRIL: Un point de contrôle est construit car les rues sont presque vides en raison de la pandémie de coronavirus (COVID-19) à Banjul, Gambie, le 04 avril 2020. (Photo de Yusupha Sama / Anadolu Agency via Getty Images)
SINGAPOUR – 06 AVRIL: Des travailleurs étrangers sont vus dans le couloir du dortoir S11 à Punggol le 6 avril 2020 à Singapour. Environ 20 000 travailleurs étrangers au dortoir Westlite Toh Guan et au dortoir S11 à Punggol sont en quarantaine après que les dortoirs ont vu une augmentation du nombre de nouvelles infections à COVID-19. (Photo par Suhaimi Abdullah / Getty Images)
Une mère portant un masque facial et des gants tient son fils après avoir effectué 14 jours de quarantaine dans un hôtel pendant le verrouillage national imposé par le gouvernement en tant que mesures préventives contre la propagation du coronavirus COVID-19, à la périphérie de Srinagar le 6 avril 2020 (Photo de Tauseef MUSTAFA / AFP) (Photo de TAUSEEF MUSTAFA / AFP via Getty Images)
Un infirmier de l’équipe médicale du Elmhurst Hospital Center réagit après être sorti de la salle d’urgence, le samedi 4 avril 2020, dans le Queens borough de New York. Le nouveau coronavirus provoque des symptômes légers ou modérés pour la plupart des gens, mais pour certains, en particulier les personnes âgées et les personnes ayant des problèmes de santé existants, il peut provoquer une maladie plus grave ou la mort. (Photo AP / Mary Altaffer)
Sanitarios de primeros auxilios de Protección Civil colocan una mascarilla de oxÃgeno a un hombre presuntamente infectado por el coronavirus, el 3 de abril de 2020 en ParÃs (AFP / Archivos | Lucas Barioulet)
Bodies are wrapped in protective plastic in a holding facility at Daniel J. Schaefer Funeral Home, Thursday, April 2, 2020, in the Brooklyn borough of New York. The company is equipped to handle 40-60 cases at a time. But amid the coronavirus pandemic, it was taking care of 185 Thursday morning. (AP Photo/John Minchillo)
Doctors tend to a patient arriving on a wheelchair at the reception of the Emergency Room, set up in a tent, in a courtyard of the Henri Mondor Hospital in Creteil, near Paris, on March 30, 2020, on the fourteenth day of a lockdown aimed at curbing the spread of COVID-19 (novel coronavirus) in France. (Photo by BERTRAND GUAY / AFP) (Photo by BERTRAND GUAY/AFP via Getty Images)
Pope Francis gathers his thoughts during Palm Sunday mass behind closed doors at St. Peter’s Basilica on April 5, 2020 in The Vatican, during the lockdown aimed at curbing the spread of the COVID-19 infection, caused by the novel coronavirus. (Photo by Alberto PIZZOLI / POOL / AFP) (Photo by ALBERTO PIZZOLI/POOL/AFP via Getty Images)
A resident using an improvised face shield made from a plastic water tank to protect him from the COVID-19 coronavirus pandemic walks in his neighbourhood in Manila on April 5, 2020, after the government imposed enhanced quarantine measures in the city. (Photo by Ted ALJIBE / AFP) (Photo by TED ALJIBE/AFP via Getty Images)
Personal médico retira un cadáver del Centro Médico Wyckoff Heights, el jueves 2 de abril de 2020, en Nueva York. (AP Foto/Mary Altaffer)
Shoppers wearing face masks with a cart full of food supplies wait in line to pay at a supermarket counter in Singapore, Tuesday, Mar. 17, 2020. Singaporeans were seen buying food supplies in supermarkets following neighboring Malaysia’s announcement of a nationwide lockdown from the coronavirus to begin Wednesday which could affect the flow of food supplies to the city state. (AP Photo/Ee Ming Toh)
04 April 2020, Lower Saxony, Hanover: Hospital beds are available in the makeshift clinic on the exhibition grounds, which was visited by Minister President Weil on the same day. The measures taken to contain the virus have currently had less effect than desired. Photo: Peter Steffen/dpa (Photo by Peter Steffen/picture alliance via Getty Images)
04 April 2020, Lower Saxony, Hanover: The makeshift clinic on the exhibition grounds, which was visited by Minister President Weil on the same day. The measures taken to contain the virus currently showed less effect than desired. Photo: Peter Steffen/dpa (Photo by Peter Steffen/picture alliance via Getty Images)
A ‘keep your distance’ sign outside Boscombe pier, as the UK continues in lockdown to help curb the spread of the coronavirus.
John Lewis and Waitrose staff latest to get coronavirus bonus
Aerial view of employees digging graves at Vila Formosa cemetery, in outskirts of Sao Paulo, Brazil on March 31, 2020. – Vila Formosa cemetery, the largest in Latin America with an area of 780 thousand square meters and where more than 1.5 million people were buried, had a 30% increase in the number of burials after the beginning of the COVID-19 pandemic. (Photo by NELSON ALMEIDA / AFP) (Photo by NELSON ALMEIDA/AFP via Getty Images)
03 April 2020, Saxony, Dresden: ILLUSTRATION – A dental technician puts on protective goggles and wears an FFP3 respirator (posed scene) before treating a corona patient in a dental office. Photo: Robert Michael/dpa-Zentralbild/dpa (Photo by Robert Michael/picture alliance via Getty Images)
Families stands and watching the burial process of their family who died by coronavirus (Covid-19) at the burial site in Jakarta, on April 2, 2020. The Covid-19 coronavirus case in Indonesia is continue to increase, as of April 2, the government officially confirmed 1.790 cases, with 112 recovered and at least 170 fatalities. Taking Indonesia to the most fatalities in South-East Asia. (Photo by Aditya Irawan/NurPhoto via Getty Images)
03 April 2020, North Rhine-Westphalia, Duesseldorf: Karl-Josef Laumann (CDU), Minister of Health of North Rhine-Westphalia, speaks during a press conference. The state government will report on the current situation and the measures taken by the state government in the context of the corona pandemic as well as on cross-border cooperation with the Netherlands and Belgium. Photo: Federico Gambarini/dpa (Photo by Federico Gambarini/picture alliance via Getty Images)
BEIJING, March 28, 2020 — Cemetery staff members leave after helping clean the tombstone and offer flowers at the Babaoshan People’s Cemetery in Beijing, capital of China, March 28, 2020. People can ask the cemetery staff to help clean tombs and offer flowers to the deceased on their behalf via the reservation service system in Beijing around the Tomb-sweeping Day, which falls on April 4 this year, as methods to prevent mass gatherings amid the COVID-19 outbreak.(Photo by Peng Ziyang/Xinhua via Getty) (Xinhua/Peng Ziyang via Getty Images)
ANKARA, TURKEY – APRIL 03, 2020: A man walks through a mobile disinfection chamber for citizens in Mamak district amid the coronavirus COVID-19 outbreak.- PHOTOGRAPH BY Altan Gocher / Barcroft Studios / Future Publishing (Photo credit should read Altan Gocher/Barcroft Media via Getty Images)
Medical staff carry a patient infected with the COVID-19 onboard a medicalized TGV high speed train at the railway station in Strasbourg, eastern France, on April 3, 2020, prior to his evacuation, along with 23 other patients, to hospitals in Bordeaux southwestern France, where the outbreak of the Covid-19 pandemic caused by the novel coronavirus (COVID-19) has been limited so far. (Photo by PATRICK HERTZOG / POOL / AFP) (Photo by PATRICK HERTZOG/POOL/AFP via Getty Images)
STRASBOURG, FRANCE – APRIL 03: An official with a protective suit carries out disinfection work for trams in central Strasbourg, eastern France on April 03, 2020. (Photo by Elyxandro Cegarra/Anadolu Agency via Getty Images)
Gardai stop and question people at a checkpoint on O’Connell Street in Dublin as the Covid-19 crisis continues. (Photo by Niall Carson/PA Images via Getty Images)
Enfermeiro fotografa impacto do coronavírus nos hospitais da Itália
Similarly, 13% of a group were at higher risk due to recent travel or exposure to a sick person.
On board the aircraft carrier USS Theodore Roosevelt, where one crew member died from the virus, « the rough numbers are that 40% are asymptomatic », said Vice Admiral Phillip Sawyer, deputy commander of naval operations.
A hospital in New York City tested all pregnant women who came to give birth over a two-week period.
Nearly 14% of those who arrived with no symptoms of Covie-19 turned out to have it.
Of the 33 positive cases, 29 had no symptoms when tested, although some developed them later.
Previously, tests on passengers and crew from the Diamond Princess cruise ship found that nearly half who tested positive had no symptoms at the time.
Researchers estimate that 18% of those infected have never developed it.
These studies have used tests that look for pieces of the virus in the throat and nose pads, which may be missing cases.
Someone can test negative one day if there is not much virus to detect and then positive the next.
Symptoms may also not appear when someone is tested, but appear later.
One Japanese study found that more than half of those who had no symptoms when they tested positive later felt ill.
Better answers may come from newer tests which check blood for antibodies, substances the immune system makes to fight the virus. But the precision of these also remains to be determined.
If infections are more widespread than previously understood, it is possible that more people have developed some level of immunity to the virus.
That could stifle the spread through herd immunity, but scientists caution that there is still much to learn about whether mild illnesses confer immunity and how long it might last.
It will likely take months before enough reliable tests have been done to answer these and other questions, including the spread of infections and the true death rate from the virus, which has only been estimated so far. .