Dr. HV Vasu is an experienced doctor who was also involved in the Triage doctors’ team that worked with Covid-19 patients in Karnataka. He was under home isolation for three weeks after he was tested COVID-positive. He used the quarantine time to reflect on a very pertinent question of whether a person could be affected by Corona more than once?
Why is this question important to someone like me who has just recovered from Corona? One. To know whether I can roam freely from tomorrow without the fear of corona being infected by Corona again. Two, even if I wouldn’t be affected by Corona again, is it possible that I will be spreading it to someone else? If answers are unknown for both these questions, then I will have to be extremely cautious in the next few days. Hence, this was the first point of my quarantine reading. There are reasons why scientists are worried about this. How effective would the vaccines currently under investigation be? Even if vaccines are out, would a single dose of it suffice? Is herd immunity a possibility in the near future? The answer to all these questions, first we would need an answer to the question ‘For how long would they be not affected with Corona again?’
There are two ways in which a person would be immunized against a virus. Firstly, when a person is infected, the body produces antibodies to fight it off and expel the infection from the body; other through T cells. While antibodies and T cells build immediate immunity as a response, long term immunity is built with the help of Memory Cells. This would help the body fight it out if the same infection enters the body again. However, not in case of all diseases will one’s body be able to fight infection throughout one’s life. Secondly, vaccination also helps build one’s immunity. While we were able to eliminate Small Pox with a one-time vaccination, in the case of other diseases like measles or tetanus, vaccination needs to be taken more than once.
In the case of Covid-19, there is no doubt that antibodies proliferate even after this corona infection. However, researches to date have not been conclusive of how long would the antibodies work, whether it would last long to prevent reoccurrence, and whether the anti-bodies produced are the same in every person infected with the coronavirus. Researches to date suggest that these antibodies can prevent the reoccurrence of coronavirus for a time-span of 40 days to 4 months. Many research on monkeys and in laboratory settings confirm this claim. Some researches have also found that patients with severe symptoms have higher levels of immunity. However, a greater presence of antibodies does not necessarily mean that the person has a greater immunity or resistance. It also doesn’t mean that a person with a lesser presence of anti-bodies is more likely to be infected again. As already stated above, immunity is not developed only by antibodies but can also be built by T cells. Also, not all antibodies produced against coronavirus can guarantee immunity against corona. What is particularly important to know is whether there exist neutralizing antibodies that can kill the coronavirus.
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In the case of SARS (Covid-19 is largely understood as SARS-2) infected patients, these neutralizing antibodies were found to be present for about 2 to 3 years. In the case of another coronavirus MERS, (MERS-CoV is the virus that caused the Middle East Respiratory Syndrome) neutralizing antibodies were found to be present for about three years. It should be noted that SARS has not reappeared since 2004 and MERS has been reported in negligible numbers.
How many cases of coronavirus (It must be understood that Coronavirus in this context refers to Corona-2 as there exist other Corona Viruses as well) reoccurrence have been found to date? There isn’t a case to be sure. This does not mean that those who were infected earlier and recovered have not been tested Corona Positive again. But in such cases, there are doubts about the tests and that there might have also existed a very small amount of latent infection, which could lead to positive reporting of coronavirus again. Keeping aside the rumors, there exist no documented examples of Corona reoccurrence.
However, the World Health Organization in its update on 24th April has stated that the presence of antibodies must not be considered as a certificate of immunity. So, what does this mean? Why does the world of science say so when it claimed that cases of reoccurrence of corona so far have been suspicious? Both of them must be understood differently. The mere presence of antibodies alone does not mean that they are immune and they cannot travel anywhere they want. This is very different from the fact there has been no precise case of corona reoccurrence after a person has recovered from the same.
According to some estimates, the quantity of research about Corona-2 Virus is much higher than any other disease. Yet, we have not had enough researches to claim conclusions regarding it. It might even take a year to reach any conclusions.
But the news in the media is alarming. In the times of confusing and contradicting claims being published scientific research journals, we cannot expect anything more from media houses that do not even hesitate to cast a lie for in their run for breaking news and sensationalizing. To quote an example, the Washington Post had published an article titled ‘Can you get coronavirus twice? Doctors are Unsure, even as anecdotal reports mount. Based on this article, India’s Livemint published an article titled COVID-19 reinfection cases increase, doctors clueless. There exists a huge difference between doctors being unsure about the Covid-19 reoccurrence cases and the doctors not being clueless (or knowing what to do) about it. The report opens with the claim that this case of reoccurrence is not a documented one and that the doctors disagree. However, experts have not yet claimed or proved that there cannot be a reoccurrence.
In Conclusion: Immunity would develop once a person is infected with the coronavirus. It is difficult to come to definitive conclusions about its quantity or the duration it would work for. Hence, it is advisable to continue with general precautions. For now, people who have already recovered from Covid-19 virus are relatively at a lower risk than others who are not yet affected. The immune system will last a little longer for those who were infected with coronavirus and had symptoms of the same. For them, there is very little chance of reoccurrence of Covid-19 in this season until there is a significant development (mutation) in the virus itself, which would leave the immunity acquired by now useless.
Translated from Kannada to English by Shashank SR