I’m a Virologist, and I’m Setting the Record Straight on Variants and Reinfections
Opinion
Jeremy Kamil
The blitz of Omicron variants has felt like one long wave. And many questions have arisen amid the tumult. Are we seeing the emergence of entirely new coronavirus variants that are impervious to immunity from vaccines and previous infections? If we keep getting reinfected, is it inevitable that most of us will end up developing long Covid? In short, the answer is no. As a virologist, it’s important to me that people understand Covid-19 remains a great concern. But this does not excuse or license a misdiagnosis of the current situation. Let’s start with what is true. BA.5, one of the most recent Omicron variants to emerge, is everywhere. It unquestionably has an advantage in terms of transmissibility over previous Omicron lineages, most likely because it’s better at evading our existing repertoire of antibodies. BA.5 and its close cousin BA.4 have a key mutation that enables them to sneak past an important class of so-called broadly neutralizing antibodies. These particular antibodies did a great job of preventing infections from a wide swath of earlier variants. That’s changed in some ways. In recent weeks I’ve watched many vaccinated friends and family members get infected with the coronavirus for the first time. The most concerning of these are cases like a colleague of mine who was infected in May and again in June, both times becoming ill. Thankfully, reinfection a few weeks after recovery is not the norm. Scientists have shown that people who previously contracted Covid-19 are less likely to get infected with the variant du jour than people who had never seen the virus, and this trend holds true for Omicron. Early research from Qatar that has not yet been peer-reviewed showed that people who had a BA.1 infection in, say, January were significantly less likely to experience a BA.4 or BA.5 breakthrough infection months later. While more research on this is welcome, these findings are consistent with how immunity, played out at the population level, helps explain the rise, fall and magnitude of epidemic waves. Antibodies remain a powerful defense against this coronavirus. They do many things to protect us, while also flagging the virus for destruction by other elements of the immune system. Even though some studies have found that Omicron variants may induce weaker antibody responses than earlier variants, this is most likely because Omicron causes less severe disease, thanks to immunity from vaccines and prior infections. Our immune system works much like a wise yet frugal investor, calibrating responses according to the magnitude and extent of the various danger signals sensed during infection. Generally speaking, the greater the symptoms and disease from infections like Covid or the flu, the stronger the antibody response. When existing antibodies are good enough to keep disease to a minimum (because fewer virus particles succeed in replicating in the body), we tend to see much lower amounts of antibodies than when someone ends up hospitalized from the coronavirus. Vaccines are a great way around that problem: They stimulate our immune systems to make antibodies, and other tailored defenses, even when there is no disease. Right now the immunological makeup of the population is a mix. People who were infected with prior variants may now be catching Omicron infections, even if they’re also vaccinated. People who have never had Covid may be getting it now. It’s true that some people who got infected from an earlier Omicron variant in December, January or even more recently are catching BA.5 now, and becoming sick from it. Alas, this current situation, where some are newly susceptible to infection while others remain protected, is no friend to nuance. It’s difficult to generalize broadly and make bold predictions concerning how well an individual or a population will hold up against infection now or later. But despite Omicron’s knack for circumventing antibodies, it’s clear that prior immunity, be it from vaccines or previous infections, protects from severe outcomes such as death and hospitalization. There has yet to be a variant that negates the benefits of vaccines. Recently, an early study, which was not peer-reviewed, argued that reinfections are just as dangerous as primary infections, but there is by no means a consensus on this among scientists and medical experts. (The study only really showed that getting reinfected is worse than not being reinfected.) Other scientists are concerned about the long-term risks of multiple reinfections. However, there is no debate that prior immunity, in most cases, reduces the severity of subsequent infections. Catching the coronavirus more than once or after vaccination does not necessarily put someone at risk for the most serious and chronically debilitating forms of long Covid, though more research is needed to understand what might predispose someone to that. The Food and Drug Administration should move swiftly to authorize new booster shots that target Omicron variants. The existing data suggest that updated shots, even based on earlier Omicron lineages, would be more effective at preventing infections than continuing to use the current vaccine boosters, which are based on the original 2019 coronavirus spike. In the meantime, if you are eligible, it’s wise to get boosted with the currently available shots, which are still outstanding at preventing hospitalization and death. (This is especially critical for older people.) Wearing a mask when mixing indoors and avoiding indoor dining when case numbers are high remains advisable for those who’d prefer not to kick the tires on their existing immunity. Fortunately, monoclonal antibody cocktails are available that remain effective against BA.5. One such product, Evusheld, is given prophylactically to protect patients, while others are used to treat severe infections. Paxlovid, which can be taken at home, may also be a good option for people who test positive and are eligible for it. Most immunologists I know are cautiously optimistic about our long-term prospects. We don’t know exactly what this virus will do next, and we should never be dismissive of those who have a high risk profile or are dealing with long Covid. Nonetheless, most of us can have faith in our immune systems, especially when we make use of vaccines and boosters. Recorded history may hold little precedent for the ongoing Covid-19 pandemic. But this is not our immune systems’ first rodeo. The New York Times
from Asharq AL-awsat https://english.aawsat.com/home/article/3777716/jeremy-kamil/i%E2%80%99m-virologist-and-i%E2%80%99m-setting-record-straight-variants-and
No comments:
Post a Comment