Everybody believes that after recovering from COVID19, they don’t have to worry about reinfection. Is this true? If yes, then how long this immunity will last?
Matt Frieman, a coronavirus researcher at the University of Maryland School of Medicine in Baltimore, says : “I think there’s a very likely scenario where the virus comes through this year, and everyone gets some level of immunity to it, and if it comes back again, we will be protected from it — either completely or if you do get reinfected later, a year from now, then you have much less disease.”
There are four seasonal coronaviruses. All these virus cause about 10 to 30% of common colds. Unfortunately, reinfection is an issue with all these coronaviruses.
We have been exposed to all these common coronaviruses since childhood. Yet, we are getting affected by them again and again.
In fact, we do have some levels of antibody to the four different coronaviruses. But, they are not able to protect us from either common colds or other symptoms.
Because, the levels of antibodies are low, and these levels slowly decline, making us susceptible again and again.
“Almost everybody walking around, if you were to test their blood right now, they would have some levels of antibody to the four different coronaviruses that are known,” says Ann Falsey of the University of Rochester Medical Center.
“Most respiratory viruses only give you a period of relative protection. I’m talking about a year or two. That’s what we know about the seasonal coronaviruses,” says Falsey.
Vineet Menachery, who is based in the University of Texas Medical Branch in Galveston, says, We work with some common cold coronaviruses. We have samples from 30 years ago, strains that were saved from 30 years ago, and they’re not appreciably different than the ones that are circulating now”.”
Some people sickened by SARS, the dangerous coronavirus that emerged in China in 2002, did develop a measurable immune response that lasted a long time.
“We’ve gone back and gotten samples from patients who had SARS in 2003 and 2004, and as of this year, we can detect antibodies,” says Stanley Perlman of the University of Iowa. “We think antibodies may be longer lasting than we first thought, but not in everybody.”
Still, it’s hard to predict how those survivors’ bodies would react if they were exposed to the SARS virus again. “There were 8,000 cases, the epidemic was basically brought to an end within six months or eight months of the first case, so we don’t have anyone who was reinfected that we know of,” says Perlman.
Understanding the natural immune response to this virus is important for vaccine development, he notes.
“If the natural infection doesn’t do very well in giving you immunity, what is going to happen with the vaccine?” says Perlman. “How are we going to make sure that that vaccine not only induces a response that works for the next six months, but two to three years?”