America has seen a general shortage of COVID-19 testing with no vaccine in sight. So what happens when the coronavirus returns without ceremony?
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said the new coronavirus “may come back” year after year. “The ultimate change in this area will be a vaccine,” he said. But that, according to Fauci, could take 12 to 18 months.
Immunity to coronaviruses differs from other diseases.
“We will not have a vaccine by next winter,” added Poland. “The southern hemisphere is just starting its fall and winter. They will have a severe course of this disease due to less preparation, less medical infrastructure and less public infrastructure. “
Immunity to coronaviruses differs from other diseases. Vaccinations against smallpox, measles or hepatitis B are expected to last a lifetime, said Poland. Coronaviruses, first discovered in the 1960s, interact with our immune system in unique and different ways, he added.
How do other coronaviruses compare to SARS-CoV-2? People infected with SARS-CoV, an epidemic that raged in southern China and Hong Kong from 2002 to 2004, were immunized for about two years; studies suggest that antibodies disappear six years after infection.
For MERS-CoV, a coronavirus that has caused hundreds of cases in the Middle East, people maintain their immunity for about 18 months – although the long-term response to further exposure to the virus may depend on the severity of the illness. ‘original infection.
The world, said Poland, should prepare for the second round: “We will start entering our summer when they enter their winter,” he said. “If, as is likely, we do not limit all travel, cases will start to return to the northern hemisphere and we will have another epidemic this fall. “
It is too early for collective immunity to be effective
Without a vaccine, “collective immunity” is another option. This theory, briefly seen in the UK as an alternative to business closings and the practice of social distancing, was deemed too risky. Ultimately, enough people should be immunized to protect the most vulnerable.
“There is no way that immunity will be high enough to achieve collective immunity,” said Poland. “With the flu, you need 60% to 70% collective immunity. With measles, you need about 95%. With COVID-19, it’s somewhere in the middle. “
In the absence of a vaccine, Poland has declared that several conditions are necessary for collective immunity to work: a very high level of immunity of the population, for this immunity to be lasting and for the virus to mutate not. “None of these currently appear to be operational,” he said.
In the United States, just over 4.1 million people have been screened for SARS-CoV-2, there are 824,147 confirmed cases and nearly 45,000 deaths. Testing has been delayed by the shortage of reliable testing nationwide. A recent Reuters poll suggested that 2.3% had been diagnosed with COVID-19.
With the flu, you need 60% to 70% collective immunity. With measles, you need about 95%. With COVID-19, it’s somewhere in the middle.
In addition to the level of collective immunity (or lack thereof) to protect those who are most vulnerable, people will need to be aware of the spread of the disease by asymptomatic carriers – that is, people who are infected but showing no signs that they are bad.
For example, a study by the New England Journal of Medicine published this month found that 29 (or 14%) of the 210 pregnant women arriving at New York – Presbyterian Allen Hospital and Columbia University Irving Medical Center tested positive for COVID- 19, but showed no symptoms.
“Our use of universal SARS-CoV-2 screening tests in all pregnant patients presenting for childbirth revealed that at this stage of the New York pandemic, most patients who were positive for SARS- CoV-2 at delivery were asymptomatic, “concludes the study.
“It highlights the risk of Covid-19 in asymptomatic obstetric patients,” added the study, released earlier this month. “In addition, the true prevalence of the infection may be underreported due to the false negative results of the SARS-CoV-2 tests.”
Spanish influenza immunity lessons of 1918
What will happen if or when SARS-CoV-2, which causes COVID-19 respiratory disease, returns? “We are only 14 weeks old, so nobody knows,” said Poland. If it has a slight mutation, he added, our antibody response will be “moderately irrelevant”.
We cannot expect to have the same “collective immunity” or “original antigenic sin” – the ability of our immune system to remember a virus that is similar, but not identical, as a previous version – to influenza. The flu, after all, has been around for 500, if not 1,000 years.
“During the Great Influenza Pandemic of 1918, the age group that died disproportionately was the young, not the elderly,” said Poland. “Older adults had seen glimpses of this virus in previous years, probably in the late 1800s, so they had an immunological memory. “
“The COVID-19 sweet spot could be from October to May. “
There are similarities between the flu and SARS-CoV-2, and they have almost identical symptoms – fever, cough, night sweats, sore bones, fatigue, nausea and diarrhea in the most severe cases. Like all viruses, none can be treated with antibiotics.
They can both be spread by respiratory droplets from coughing and sneezing, but they come from two different virus families – and ongoing research to develop a universal flu vaccine shows just how much influenza viruses and coronaviruses can be difficult.
“The second wave of the 1918 Spanish flu was even more devastating than the first wave,” said Ravina Kullar, infectious disease specialist at the Infectious Diseases Society of America and adjunct faculty member at the University of California in Los Angeles.
Historians believe that a more virulent strain of influenza struck during three difficult months in 1918 and spread by troops crossing Europe during the First World War. It would be the worst case for a second wave of SARS-CoV-2 this fall or winter.
“It will likely strike more severely in areas that were not severely affected the first time inside the United States, where there are many more susceptible people,” said Kullar. “The COVID-19 sweet spot could be from October to May, with a peak, probably, in October and November. “
Kullar said scientists are learning something new every day from modeling studies. “If it follows the same pattern as the flu, it will likely stabilize during the summer,” she said. “If there is immunity, the virus will likely come back to find new victims.”
Tests will determine the rate of asymptomatic carriers
What else, apart from social distancing to “flatten the curve” of new infections, can we do in the meantime? As scientists work to crack the code for the new coronavirus, government and members of the public can work together.
There is reason to be optimistic. “We still have a lot to learn about the flu, even though we have had flu vaccines since the mid-1940s,” said Poland. “It’s amazing what the world has done in 14 weeks on COVID-19, but what’s more amazing is how much there is still to learn. “
During these 14 weeks, scientists around the world have learned a lot about SARS-CoV-2, including the genetic structure of the virus; how it infects human cells; what type of manifestation of the disease it causes; and how it affects the liver, kidneys and brain.
“It all comes down to tests. “
“It all comes down to testing,” said Kullar. “We really need to have large-scale tests and search for contacts to find all those who have been exposed and have them isolate for 14 days. We don’t have a system like this in the United States right now. “
On Monday, more than 50 days after the first case of coronavirus was reported in New York, the state began random antibody testing on willing grocery customers in different parts of the state. There is no guarantee at this time that the presence of antibodies confers immunity.
The procedure, also known as a serological test, uses a finger-drawn blood sample. It will analyze 3,000 people across New York, which has a population of 19.5 million, over the next week, Governor Andrew Cuomo said on Sunday. But questions remain about the effectiveness of the tests.
Assuming the tests are up to date by the end of the summer, Kullar says the Americans should be on a good footing for the second round of SARS-CoV-2 with, ideally, enough supplies and hospital tests in place to make sure we make fewer mistakes next time. about.
But many will return to the American people. “The way we behave will really determine the extent of this virus,” she said. “Maintain social distance and wear masks in public until we see infection rates go down, and continue until we get enough tests.” “