The coronavirus is certainly scary, but despite constant reports on the total number of cases and the increasing number of deaths, the reality is that the vast majority of people who descend with COVID-19 survive it. As the number of cases increases, so does another number: those who have recovered.
By mid-March, the number of patients in the United States who had officially recovered from the virus was close to zero. This number is now in the tens of thousands and is increasing every day. But recovering from COVID-19 is more complicated than just feeling better. Recovery also involves biology, epidemiology and a little bureaucracy.
How does your body fight COVID-19?
Once a person is exposed to the coronavirus, the body begins to produce proteins called antibodies to fight the infection. As these antibodies start to contain the virus successfully and stop it from replicating in the body, the symptoms usually start to decrease and you start to feel better. Ultimately, if all goes well, your immune system will completely destroy all the viruses in your system. A person who has been infected and has survived a virus with no long-term health effects or disabilities has “recovered”.
On average, a person infected with SARS-CoV-2 will feel sick for about seven days after the onset of symptoms. Even after symptoms have subsided, there may still be small amounts of virus in the patient’s system, and they should remain isolated for three more days to make sure they have really recovered and are no longer infectious.
What about immunity?
In general, once you have recovered from a viral infection, your body will keep cells called lymphocytes in your system. These cells “remember” the viruses they have already seen and can react quickly to fight them again. If you are exposed to a virus that you have already had, your antibodies will likely stop the virus before it starts to cause symptoms. You become immune. This is the principle of many vaccines.
Unfortunately, immunity is not perfect. For many viruses, such as mumps, immunity may decline over time, leaving you vulnerable to the virus in the future. This is why you need to be vaccinated – these “reminders” – on occasion: to stimulate your immune system to make more antibodies and memory cells.
Since this coronavirus is so new, scientists still don’t know if people recovering from COVID-19 are immune to future virus infections. Doctors find antibodies in sick and cured patients, which indicates the development of immunity. But the question remains how long will this immunity last. Other coronaviruses like SARS and MERS produce an immune response that will protect a person for at least a short time. I suspect the same is true for SARS-CoV-2, but research has simply not yet been done to say it definitively.
Why have so few people officially recovered in the United States?
It is a dangerous virus, which is why the Centers for Disease Control and Prevention are extremely careful when deciding what it means to recover from COVID-19. Medical and screening criteria must be met before a person is officially declared recovered.
Medically, a person should be fever-free without anti-fever medication for three consecutive days. They should show an improvement in their other symptoms, including a reduced cough and shortness of breath. And it should last at least seven full days since the symptoms started.
In addition to these requirements, the CDC guidelines state that a person must test the coronavirus negative twice, with testing done at least 24 hours apart.
It is only then, if the symptoms and conditions of the test are met, that a person is officially considered recovered by the CDC.
This second testing requirement probably explains why there were so few officially recovered cases in the United States until the end of March. Initially, there was a massive shortage of tests in the United States. While many people are certainly recovering in the past few weeks, this could not be officially confirmed. As the country enters the height of the pandemic in the coming weeks, the focus is still on finding those who are infected, not those who have probably recovered.
Many more people are being tested now that states and private companies have started producing and distributing tests. As the number of tests available increases and the pandemic eventually slows down in the country, more tests will be available for those who appear to have recovered. As people who have already recovered are tested, the appearance of any new infection will help researchers know how long immunity can last.
Once a person has recovered, what can they do?
Knowing whether or not people are immune to COVID-19 after recovery will determine what individuals, communities and society in general can do in the future. If scientists can show that recovered patients are immune to the coronavirus, then a recovered person could theoretically help support the health care system by caring for those who are infected.
Once communities reach the peak of the epidemic, the number of new infections will decrease, while the number of people recovered will increase. As these trends continue, the risk of transmission will decrease. Once the risk of transmission has diminished enough, community isolation and social distancing orders will begin to ease and businesses will begin to reopen. Other countries have experienced that it will take months before the risk of transmission is low in the United States.
But before all of this can happen, the United States and the world must get through the peak of this pandemic. Social distancing slows the spread of infectious diseases and works for COVID-19. Many people will need medical help to recover, and social isolation will slow the virus down and give people the best chance of getting it.
Tom Duszynski, director of education in epidemiology, IUPUI
This article is republished from The Conversation under a Creative Commons license. Read the original article.