A friend of mine, after having two vaccinations and three boosters against Covid-19, came down with Covid anyway. She spent two weeks in quarantine, then tested negative and began leaving her house. A week later, she got Covid again. You’d think that after five vaccinations and a bout of Covid you’d be protected from re-infection, at least for a while. You aren’t.
Another friend tells me he’s had Covid five times, even though he’s had all his shots.
Since I’ve written a book about the pandemic (Pandexicon), people tend to tell me about their experiences with the disease. Especially when their experiences don’t fit the patterns established by researchers and assumed by health authorities. Dozens of studies suggest that infection by Covid confers protection against being infected again. That was the thinking behind adopting a policy of “herd immunity” -- the notion that if you let the disease run unchecked through a population, eventually that population will become immune and the disease will die out.
Alas, it doesn’t work that way.
The most recent study, conducted by the University of Washington’s Institute for Health Metrics and Evaluation and published last month in the medical journal The Lancet, suggests that a bout of Covid confers a “very high” degree of immunity against being infected again. This sounds like good news, but not as good as the right-wing media thought it was. Even mainstream news sources caught the bug. NBC announced that “immunity acquired from a Covid infection provides strong, lasting protection against the most severe outcomes of the illness — protection, experts say, that’s on par with what’s provided through two doses of an mRNA vaccine.” That seems to confirm that if you’ve had Covid, you don’t need to be vaccinated.
But that isn’t what the study says.
The University of Washington study meta-analyzed 65 reports from 19 countries, and found that people who had had Covid showed a reduced risk of reinfection: the authors conclude that, overall, a previous case of Covid was, on average, 78 percent effective in preventing future infections from all previous coronavirus variants.
But thinking that “natural immunity” (from previous infection) is better than “artificial immunity” (from vaccination) is a misinterpretation of the study. The authors still recommended that we get vaccinated and receive booster shots at least once a year.
Why?
For one thing, the mean immunity conferred by a previous case of Covid – 78 percent – is lower than that provided by a vaccine: Pfizer, Moderna, and Astra-Zeneca confer an initial immunity higher than 90 percent.
For another, the Lancet study found that although there was a “high level” of natural immunity against the original coronavirus strain that hit us in 2020, there was less protection against the Alpha, Beta and Delta variants, and immunity was “substantially lower” against Omicron, which is the variant we’re dealing with now. A person who contracted Covid before Omicron is only 36 percent protected against reinfection by Omicron.
And the study didn’t even look at anyone who had been infected by Omicron sub-variant, XBB.1.5 (also known as Kraken).
An earlier study conducted in India found that a single, initial vaccination plus a case of Covid provided the same protection as two vaccinations, suggesting that a person who has had Covid needs only the initial vaccination and can skip the second. The Lancet study seems to support that notion, and it might prove useful for health authorities preparing their policies against future waves of Covid. The British Journal of Medical Ethics notes that, in the past, before mandating vaccinations, health authorities “should have recognized natural immunity as a sufficient basis for exemption from vaccination requirements.” If future health authorities take natural immunity into account when rolling out vaccines for the next pandemic, governments in wealthy countries might not be so inclined to horde vaccine doses for their own citizens, and might allow more doses to be made available to low- and middle-income countries, which remain, after three years of the present pandemic, woefully under vaccinated.
But these are policy considerations, based on meta-analyses, and don’t say much about how vulnerable we are as individuals. The World Health Organization has called Kraken the most transmissible variant of the SARS-CoV-2 coronavirus yet; since last year, more people have been infected by Omicron than by all previous variants combined.
This disease is not going away. And as my friends’ experiences have shown, having had it once does not mean we can’t get it again. And again.
Plus the risk of Long Covid.