The coronavirus quarantine could last much longer than expected.
A new study suggests that individual immunity to COVID-19 cannot last more than a couple of months, meaning that a person could be reinfected. It is a possibility that, if true, will have serious implications for our ability to contain the pandemic.
The document, which has not yet been peer-reviewed, was published last week on the medRxiv prepress server. After noting that antibodies against the virus that causes COVID-19, SARS-CoV-2, are generally detectable within 10 to 15 days after a person begins to show symptoms, the researchers note that it is unclear how long they will last. these antibodies and if they immunize patients against infection again.
To determine if virus-neutralizing antibodies (nAbs) persist long enough to provide lasting protection, a group of scientists studied blood samples taken over time from 65 people who tested positive for the coronavirus, whose conditions ranged from asymptomatic. even life threatening. – for a period of up to 94 days after they initially showed symptoms.
They found that over 95% of the patients studied had developed the antibodies and carried nAbs approximately eight days after diagnosis, with peak nAb levels after an average of 23 days. However, nAb levels soon began to drop, and among patients who were evaluated after 65 days, the number that retained potent nAbs fell to 16.7%. Patients with higher nAb levels at their peak maintained them after more than 60 days, while those with no higher levels ended up returning almost to their baseline. These findings were reinforced by a similar study by researchers of 31 health workers at a different group of British hospitals.
“A wide range of neutralizing antibody titers to SARS-CoV-2 (nAb) have been reported after infection and these vary according to the period of time from infection and disease severity,” the study reads. . “Additional knowledge about the magnitude, timing, and longevity of nAb responses after SARS-CoV-2 infection is vital to understanding the role that nAbs could play in disease elimination and protection against reinfection. (also called renewed or second wave infections). “
Salon contacted Dr. Russell Medford, President of the Center for Global Health Innovation and the Global Health Crisis Coordination Center, to reflect on the study.
“This is a very good study,” Medford told Salon. “What it shows is that this is similar to what we’ve seen with the other coronaviruses in this class, that antibody titers decrease after exposure. The real problem for us now is, while true, to what extent it is that related to immunity and reducing the severity of infection in the future. And we don’t know the answer to that at the moment. “
This is not the first time that speculation has emerged as to whether humans will be able to develop immunity to the coronavirus. A doctor named D. Clay Ackerly wrote to Vox that he had a 50-year-old patient who contracted COVID-19 on two apparently separate occasions.
“Overall, the unknowns of immune responses to SARS-CoV-2 currently exceed those known,” Ackerly wrote. “We don’t know how much immunity to expect once someone is infected with the virus, we don’t know how long that immunity can last, and we don’t know how many antibodies it takes to mount an effective response.”
There is also concern that, even if an effective vaccine is developed to treat COVID-19, there are not enough people taking it for herd immunity to occur. After a survey conducted in May, found that only 49% of Americans would definitely get vaccinated if one was available (compared to 31% who are unsure and 20% who would not), Dr. Georges Benjamin He told Salon that those numbers were troubling.
“We know very clearly that if we do not cover 70% of the population, we will probably not have collective immunity,” said Benjamin, executive director of the American Public Health Association. “There are some people who think that, with this virus, we could achieve it with 50%, so it is not 100%. But I am thinking that 70-something-% is about where we should be, and it is because I have seen some of the data. We can do that with 50%, but the bottom line is if we run the risk of not getting collective immunity with the vaccine. “
