Keeping up with your COVID vaccines could have benefits beyond just topping up immunity to the latest circulating variants, according to a new study. Researchers led by a team at Washington University School of Medicine found that the antibodies generated by the vaccine have broad effectiveness against a range of variants, and might even help us build our defenses against the coronaviruses of the future.

The trouble with immune imprinting

We’ve heard a lot over the last four years about the similarities, and crucial differences, between COVID-19 and another great respiratory virus foe: influenza. 

As a seasonal disease (unlike COVID, as far as we know), each year scientists have the unenviable task of updating the flu vaccine to match their best guesses for which strains of the virus will be causing the most problems. But there’s a problem. The memory cells that are produced by the immune system in response to one year’s vaccine don’t always leave space for new antibody-generating cells the following year, meaning you get a weaker immune response. This effect is called imprinting. 

While with the flu vaccine imprinting can have a negative impact on a seasonal shot’s efficacy, no one knew whether the same could be true for COVID-19. It’s not on the same annual schedule as flu, but we’re all too aware of how readily this virus can mutate to spawn new variants, and the vaccines have undergone several rounds of updates as a consequence.

What the study found

To investigate, the team looked at antibodies from humans and mice that had received a course of mRNA COVID-19 vaccines targeting first the OG variant from the days of social distancing and sold-out toilet paper, and then the newer Omicron variants. Some of the human participants had also gained antibodies from a natural COVID infection at some point during the pandemic.

While there was evidence of imprinting from the initial vaccine, it did not seem to be having the negative impacts it can have with flu vaccines. Very few of the antibodies recovered were specific to either original COVID or Omicron – rather, the vast majority were cross-reactive, recognizing both variants of the virus. 

The researchers then tested the antibodies against a panel of different coronaviruses. There were two SARS-CoV-2 variants from different Omicron lineages, a pangolin coronavirus, the SARS virus from the 2002-2003 epidemic, and the virus responsible for Middle Eastern Respiratory Syndrome (MERS). The antibodies were able to neutralize all of these viruses except for MERS, which is more evolutionarily distinct from the others. 

The key to this cross-reactivity, the scientists discovered, was the combination of the different vaccines received. The same breadth of antibodies was not generated when people had only been vaccinated against the original COVID variant, and had not received an Omicron booster. This means that keeping abreast of the latest variants and regularly boosting the population against them could be storing up even greater benefits than simply keeping COVID at bay.

When COVID hit, we were starting from scratch. Most of humanity had not encountered a similar virus before, so there wasn’t a level of baseline immunity in the population to help protect us. This study opens the tantalizing possibility that continuing to vaccinate against COVID could mean the situation would be very different if another novel coronavirus were to come along.

“We do not know for certain whether getting an updated COVID-19 vaccine every year would protect people against emerging coronaviruses, but it’s plausible,” said senior study author Michael Diamond in a statement. “These data suggest that if these cross-reactive antibodies do not rapidly wane – we would need to follow their levels over time to know for certain – they may confer some or even substantial protection against a pandemic caused by a related coronavirus.”

What’s the latest on vaccines and the FLiRT variants?

Well, that all sounds quite promising. But given all the recent news about yet another new set of COVID variants, how are our vaccination efforts stacking up right now?

The FLiRT variants have become the latest to surge in frequency across much of the globe. One in particular, KP.2, has recently overtaken the previous big-hitter, JN.1, and is causing the greatest proportion of infections in the US. 

While KP.2 has attained some mutations that some speculate might be helping it to evade prior immunity from vaccines and infections, this new research supports what many health experts have said, that all those previous antibodies you’ve generated will still be helping to protect you. 

It is important to keep boosting your immunity though, so if it’s possible for you to access an up-to-date shot where you live – especially if it’s been a while since your last one – it might be time to consider it, or to hold out for the next round of updates. Epidemiologist Adrian Esterman told Newsweek recently that “there will be a new vaccine available around September, based on either JN.1 or one of the FLiRT subvariants, that will give much better protection.”

The vaccine landscape itself also changed recently with the withdrawal of the AstraZeneca vaccine from the global market. With their vaccine, named Vaxzevria, AstraZeneca did not take steps to update the formula based on newer virus variants coming into circulation – unlike the manufacturers of several of the mRNA vaccines, for example. 

Without these updates, Vaxzevria has likely now waned in effectiveness, and a decline in demand for their product means AstraZeneca have reportedly taken a commercial decision to discontinue it. It was a vital part of the global pandemic response when it was first developed, but now that there are so many other options – something we could only have dreamed of in the darkest days of 2020 – it seems it has had its day.

But if you were one of the millions of people who received this vaccine, this new antibody research should reassure you that the beneficial effects, combined with any booster shots you have and will continue to receive, could last long after its withdrawal is complete.

The study is published in Nature.