What COVID Breakthrough Infections Might Look Like In The Future

If you're vaccinated, here's what you may be able to expect with new COVID-19 waves and what experts still don't know.
Infectious diseases experts explain what they think breakthrough COVID-19 infections will look and feel like moving forward.
agrobacter via Getty Images
Infectious diseases experts explain what they think breakthrough COVID-19 infections will look and feel like moving forward.

When omicron ripped through the population last month, tons of people who had been fully vaccinated and boosted were surprised to find that ― after two years of avoiding the virus ― they finally tested positive for COVID-19.

The highly contagious variant taught us that while the vaccines continue to do an excellent job at protecting most people from serious illness, hospitalization and death, it’s a bit of a different story when it comes to those less severe symptomatic infections.

The bulk of breakthrough infections reported during the omicron wave were considered less severe than the infections recorded in people who were unvaccinated or only partially vaccinated. And early research suggests long COVID is significantly less likely in vaccinated people who have had COVID-19.

Some infectious diseases experts expect breakthrough infections to be similar going forward, while others are cautious about guessing how it all will play out. That said, there are some predictions based on previous waves and what we know about COVID-19 now.

What will breakthrough infections be like the next few months?

Most infectious diseases experts aren’t surprised that so many vaccinated people recently tested positive.

“The vaccines were not designed to prevent infection. They were designed to prevent severe disease, and they’ve done that extraordinarily well,” said Dr. Jaimie Meyer, a Yale Medicine infectious disease doctor and associate professor of medicine at Yale School of Medicine.

The vast majority of breakthrough infections — which Meyer prefers to call post-vaccination infections — have been mild. But it’s important to be clear about what mild entails. Dr. Julie Parsonnet, an epidemiologist and professor of infectious diseases with Stanford Medicine, stressed that mild COVID-19 illnesses can be anything from a runny nose for a couple days to being run-down and bedridden for a week. Mild infections essentially involve all the cases where people get sick but don’t end up in the hospital. It’s a wide range.

In general, fully vaccinated and boosted people tend to be in the “milder range,” according to Parsonnet, and a lot will be completely asymptomatic.

Over the next few months, as we come further off the omicron surge, we’ll likely see a lull in the number of infections occurring. We’ve seen, time and time again, that severe illness is mostly occurring in people who are unvaccinated and partially vaccinated. People who have an underlying immune condition are also more at risk for more serious disease after vaccination — but we also know that the booster provides great protection against severe outcomes in at-risk individuals. Infection mitigation measures, like mask wearing, is also vital.

“I expect that pattern will continue, although hopefully, overall, the number of infections will decline — and so the absolute number of post-vaccination infections will decline, too,” Meyer said.

There are still a ton of unknowns with COVID-19, like what may happen if a new, more contagious variant emerges. However, both experts interviewed are hopeful that the virus will continue to get less severe.
AzmanL via Getty Images
There are still a ton of unknowns with COVID-19, like what may happen if a new, more contagious variant emerges. However, both experts interviewed are hopeful that the virus will continue to get less severe.

What might breakthroughs be like be several months from now?

A small study from the Centers for Disease Control and Prevention recently found that the durability of the booster shot’s protection — specifically when it comes to urgent care and emergency room visits — may dwindle after around four months. But the three-dose series remains highly effective against severe disease over time, a CDC spokesperson told The Associated Press.

As antibody levels wane, more people will contract infections, Parsonnet said, but she does not expect those breakthroughs to become more severe over time. Think: runny noses, colds, maybe more diarrhea, she said.

Parsonnet is confident that our B cells and T cells — which are also activated when we get vaccinated and part of our long-lasting immune response to infections — will always be able to react really quickly, which lowers the risk of severity. Our T cells are always going to be there — we won’t spontaneously lose that memory.

“Once the virus gets into your bloodstream, most people are going to have a really good and effective immune response to that,” she said. These breakthroughs will also keep our immune system primed, in a way, to naturally boost our B cells and T cells that keep us safe from severe illness.

“As antibodies wane and vaccines wane, we may see more colds — but I don’t think we’re going to see a big turn back to bad disease,” Parsonnet said. The exception here is with unvaccinated people and certain immunocompromised people who can’t mount strong antibody responses after vaccination — which is why we may see boosters routinely recommended for those at risk.

Will we need another shot if a new variant emerges?

Though not expected right now, there is a chance a new variant could emerge that can outsmart our immunity even more than omicron. “It would take something really incredible to outrun it [completely],” Parsonnet said.

If virus transmission accelerates again, we may need another booster, but when that might happen — and how regularly we’ll need a boost — is unknown.

When it comes to the variant-specific shots that vaccine manufacturers are currently working on, there are a couple of issues to consider.

One, though these tailored shots might target one variant super well, they could be less effective at protecting us from other variants that emerge. This could put selective pressure on the virus, and it could mutate further to work its way around the shot, Meyer said.

Two, by the time these variant-specific shots are created, tested, manufactured and distributed, the wave may have already passed (think of how things progressed with alpha, then delta and omicron).

We may eventually see new methods of vaccination — like nasal sprays, which can block the virus from attaching to our airways and forming an infection in the first place. What we really want, according to Parsonnet, is a pan-coronavirus vaccine — a shot that will cover all the variants.

There are a lot of scientists working on these types of vaccines, but if and when they’ll be ready and available is unclear.

Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.

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