COVID-19 pandemic is not an on / off switch

During the winter surge of COVID-19, I felt that the coronavirus was everywhere.Cold weather pushed people in Where the virus can remain in the airAnd the omicron mutant that controls the surge of SARS-CoV-2, the virus that causes COVID-19, had the nasty ability to dodge several immune responses (SN: 5/18/21). in short, Both vaccinated Or, previously infected people are more susceptible than previous coronavirus variants. Perhaps it was not surprising given that the main goal of the vaccine is to prevent severe illness and death (so-called sterile immunity, not to prevent infection at all). Still, Omicron was surprised at everyone.

Finally, weeks after the proliferation of COVID-19 cases, it continues to decline in most parts of the United States and around the world. As the number of cases diminishes, I hold my breath and hope that there are no signs of resurrection. So far, very good — for now. I may be able to exhale immediately, at least for a short time. (Although the New Jersey case I live in seems to have leveled off at a level close to the peak of the delta wave last summer.)

The majority of winter COVID-19 cases were caused by a subvariant of Omicron called BA.1. Researchers are now looking at its sibling, the Omicron subvariant called BA.2.Even if the number of cases decreases overall, BA.2 is On an upward trendAccounts for an estimated 4% of new cases in the United States for the week ending February 19.

BA.2 is slightly more contagious than BA.1, which has the potential to exacerbate the current surge, and is relevant to researchers because it has several different mutations from BA.1. Both BA.1 and BA.2 Dodge virus attack antibodies Caused by vaccination or infection with other mutants, some of the differences in BA.2 may mean that antibodies produced after BA.1 infection can be avoided ().SN: 12/21/21). So far, that’s not what scientists are seeing. Instead, even if these types of reinfections can occur They are rareReported in a preliminary survey posted on medRxiv.org on February 22nd by a European team. The BA.2 reinfection found by the team was most common in unvaccinated young people who were not hospitalized. Time indicates how long this protection will last and how it will work for future variants or subvariants.

This is not the first time I have been worried about reinfection. Concerns that the emergence of alpha, beta, and gamma variants, a year before the pandemic era, in early 2021, could soon cause more people to face a second bout of COVID-19. Has occurred. So last February, I interviewed the epidemiologist Aubree Gordon at the University of Michigan, Ann Arbor, to hear her thoughts. What variants mean for pandemics in general ((((SN: 2/5/21).

At that time, our understanding of reinfection was still in its infancy. Studies have suggested that beta and gamma mutants may evade parts of the immune system and allow reinfection. However, it was not known how common reinfection was or whether the second seizure of COVID-19 was less severe than the first seizure. In the meantime, vaccine deployments in the United States have been on track, with many desperately seeking a first dose. Last year, Gordon, who is studying coronavirus reinfection, told me that a new variant could prolong the pandemic. But she quickly reminded me that the pandemic always ends, even in the face of varieties.

Fast forward in February 2022. Vaccines are more widely available (although some people still have access issues and don’t want shots) and are certainly not spring chickens when it comes to confronting new variants. However, since the pandemic is a time warp, I decided to catch up with Gordon to see if Gordon’s thinking changed after February 2021. The conversation has been edited for length and clarity.

Garciade Jesús: What have you learned about reinfection in the last year?

Gordon: One of the lessons learned about reinfection or [vaccine] The breakthrough is that when a person receives a second exposure, the first is vaccination and the second is an infection, or the first is an infection and the second is a vaccination. People generate “hybrid immunity”.People are creating a wider range [immune] Responses that will help protect them from future infections. It does not kill immunity to all the mutants that occur, but it does help reduce the likelihood that people will be infected or re-infected with all the mutants. And if they are re-infected, they will have a milder infection.

Garcia de Jesús: Last year you mentioned that booster shots may or may not be needed. What do you think now?

Gordon: Our perception of boosters has changed completely. It turns out that boosters are useful. They will help suppress transmission. They help reduce the severity of people with breakthrough infections. Vaccination with the original strain of the virus and boosting is not very effective in preventing Omicron infection, so I think you generally feel that you need a boosting that is unique to Omicron. ..

We need to look to the future. I think one of the big questions about Omicron-specific boosters is how they affect people who have already been vaccinated or who have been previously vaccinated and boosted. Do you just boost your immunity to Omicron? Or do you see them develop broader immunity? Boosting with another variant can generate broader immunity not only to protect against omicrons, but also to temporarily protect against future circulating variants.

Garcia de Jesus: It is said that as the state relinquishes the obligations of the mask, we are ending the pandemic stage of the outbreak of this virus. true?

Gordon: I think it’s a mistake to give up control completely at this point.We haven’t gone through it, we’re not endemic level [when the virus normally circulates at some baseline amount].. But I think we are in transition.

For example, looking back at the influenza pandemic, there is a transition period. The first year or two caused a great deal of damage, but after that, [transmission] It usually stays high for several years. At this point, we think most countries (most, not all) are at a stage where they have some degree of immunity. The transition period for SARS-CoV-2, the virus that causes COVID-19, actually depends on the severity of the infection and the number of exposures required to reach endemic levels. Sure, it looks like a single exposure actually reduced the severity, but perhaps it didn’t go down to endemic levels that grew after being exposed to the virus for the rest of your life. The length of the transition period and how painful it is actually depends on the severity of the reinfection that occurs over time.

Garciade Jesús: What is the pandemic epidemic?

Gordon: Endemic is the period during which the virus reaches “normal levels.”You have a high level of artificial immunity, and [the virus] It still causes certain levels of serious illness. I still don’t know what it looks like.At the stage of endemic, it is unknown whether the severity of this virus looks like a seasonal coronavirus. [that causes a cold] Or whether it looks like the severity of the flu [which can kill tens of thousands of people on average per year in the United States] Or more severe than the flu. Before we know all of that, we really need to get to where it is at endemic levels.

And the other is the infection rate. We know that people are re-infected very often with the seasonal coronavirus. On average, about every three years, even people who have been exposed to the coronavirus throughout their lives can develop it after six months. At the beginning of the pandemic, the entire population was naive to this new coronavirus. We have been boosting immunity for a long time, so transmission remains fairly high. As people boost their immunity, it will slow down, but we will see. You may need an annual booster or a regular booster. We may be able to come up with a longer lasting, broader and more protective vaccine — that would be great.

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Garciade Jesús: Do you think you are more optimistic or pessimistic than last year?

Gordon: To be honest, I’m about the same. The only thing that made me a little pessimistic was … a study done in Nicaragua. A big wave struck in 2020, infecting about 60% of the population in the survey. Then we moved forward and in 2021 there was probably another big wave of gamma and delta. What made me a little more pessimistic about the situation was The severity of recurrent infections was higher More than I expected … but I always thought I needed to be exposed at least twice [to the virus] Before approaching endemic levels. Maybe more than one, but we really don’t know. Nicaragua currently has Omicron. As a result, many people have been vaccinated, and many have already been exposed a few times. Let’s see what happens during this Omicron wave.

Garcia de Jesús: We all want to end this. How do you know

Gordon: I think people are confused about when the pandemic will end. As I said, it’s a transition period. Instead of thinking of it as a dimmer — the top is a pandemic and then slides to the bottom, which is endemic — people want it to be an off-on switch. “Oh, it’s a pandemic, and now it’s over. We’re in the endemic stage.” But unfortunately, we’re not there yet. Slowly slide towards the endemic stage.