As the COVID-19 vaccine is launched, many of those who have contracted the coronavirus are wondering whether they still need to be vaccinated. It is a vital issue rooted in the science of immunology: in fact, with some viruses, such as chicken pox, the patient is immune for life after contracting them; in the case of other viruses, like many flu, patients’ immune systems “forget” how to identify and protect against the virus after a period of time, which can be months or years. Because the new coronavirus is so new, it was not known how long after it recovered from the virus the body would remain immune, and whether it could affect anyone who received the vaccine.
Now, the Center for Disease Control and Prevention (CDC) is saying that those who have recovered from COVID-19 must still receive the vaccine. His recommendation comes, in part, due to the lack of conclusive data on how long immunity lasts after infection.
“Experts still don’t know how long someone is protected from getting sick again after recovering from COVID-19,” says the CDC.
Still, experts are working around the clock to find out. According to a new study published on Thursday, scientists at Public Health England (PHE) think that natural immunity lasts up to five months – but that is not an absolute certainty and comes with some caveats.
There have been several cases of patients who have had coronavirus twice, which is evidence that being infected does not make anyone immune forever, at least in some patients. Previous studies have suggested that natural immunity lasts between three and six months. But the new study carried out in the UK frames it in a different way. Specifically, the study found that a previous COVID-19 infection reduces the risk of reinfection by 83 percent compared to people who have not been infected before. Putting a percentage on the chance of getting infected again is useful for public health experts and citizens to calculate the risk.
The study regularly tested about 21,000 health workers for COVID-19 and COVID-19 antibodies at the UK National Health Service between June and November 2020. In that period, 6,614 participants tested positive for COVID-19 antibodies and 14,000 had no signs of previous infection. However, of those who tested positive for antibodies, 44 health workers tested positive for antibodies had “potential reinfections”, according to a press release about the study, months later.
So what does that mean?
“This means that even if you believe you have had the disease and are protected, you can be sure that it is highly unlikely that you will develop serious infections … but there is still a risk of getting an infection and passing it on to others,” said Susan Hopkins, a senior medical consultant at Public Health England and study leader, in a press release. “It is vital that we all stay home to protect our health care and save lives.”
Another equally worrying finding from the research is that previously infected people can still carry high enough levels of the coronavirus that they can continue to infect others.
“Now we know that most people who have had the virus and developed antibodies are protected from reinfection, but that is not total and we still don’t know how long the protection lasts,” said Hopkins. “Crucially, we believe that people can still transmit the virus.”
Hopkins emphasized that this study painted “the clearest picture so far of the nature of the antibody’s protection against COVID-19”, but that these “initial findings” should not be “misinterpreted”. In other words, don’t let this ruin your day.
As Salon explained earlier, it is difficult to study long-term immunity using human data because the coronavirus is very new to science. A study that gained a lot of attention published a study in the scientific journal Nature Medicine suggested that natural immunity can last up to 12 months – but this was based on the study of four different seasonal coronaviruses, not the new coronavirus (known as SARS-CoV-2) .
Some viruses, such as measles, confer lifelong immunity to those who contracted or were vaccinated against them. However, science continues to suggest that this is not the case for SARS-CoV-2. How long the immunity of the COVID-19 vaccine lasts is also unknown, but if it turns out to be a “transient immunity”, it could mean that the vaccine is not a ready deal. It may require a booster or even a seasonal vaccine – as for the flu.
“This can end up being a vaccine that is not a single thing or even twice, it can end up being like, once and a booster, or it can end up being what we call a seasonal vaccine, or vaccine that needs to be administered every two years. “said Dr. Charles Chiu, professor of infectious diseases at the University of California-San Francisco, in September. He noted that transitional immunity can cause problems for the country to achieve collective immunity as well. Public health experts hope that humans will end up eradicating the coronavirus with a combination of vaccination and mitigation strategies, such as mask use and social detachment.
“The hope is that the vaccine, while it may not be 100 percent effective or durable, is enough that, then, if we have enough tests and containment measures, we can simply eradicate the virus,” said Chiu.