How covid, flu, and other seasonal vaccine programmes are changing

Changing landscape

The world has changed since covid-19 emerged, says Ann Lindstrand, unit head of the essential programme on immunisation at WHO. The SARS-CoV-2 virus that caused millions of deaths and flung the world into chaos remains slippery: new variants keep emerging, and outbreaks in multiple countries this summer have made headlines. In the US state of Arizona, a 37% spike in cases in July prompted the unplanned relaunch of the covid-19 vaccine programme.3

Lindstrand expects that the situation will stabilise into a seasonal pattern like influenza. In a blog, Erik Topol, a cardiologist and professor at the Scripps Research Institute in the US, says that we already “have two major waves each year and, for high risk individuals, semi-annual (every 6 months) shots will be needed for protection.”4 Christina Pagel, professor of operational research at UCL, London, told Yahoo News that it was already more like an “all-year-round” virus.5

Decisions over how and when to administer flu, covid-19, or RSV vaccines vary across WHO regions. And, officially, WHO does not yet have a recommendation for seasonal covid-19 vaccination. Even flu jabs are not deemed essential. “It’s not a strong level of recommendation,” notes Lindstrand. Countries must weigh up the substantial cost of such programmes and whether immunising against flu and covid-19 is a priority.

“I was recently in a regional meeting in Africa, and the appetite for covid vaccination at this point in time is very low,” says Lindstrand. African countries might be more interested in malaria or human papillomavirus programmes, she says.

New and returning patterns

Covid-19 lockdowns greatly affected the annual pattern of disease incidence for infections such as flu and RSV, but those patterns have largely returned,6 meaning that winter vaccination programmes can help keep people out of hospital—especially in parts of the world that experience harsh winters. In the past five years, data have shown the significant disease burden of RSV, according to Lindstrand, which is partly why a vaccine against it is now offered in some countries.

From 1 September, adults aged 75 or older and pregnant women will be eligible for an RSV jab in the UK.7 This won’t be a vaccine that people receive annually—one jab is all most people will ever need—but the rollout will roughly coincide with the annual flu and covid-19 vaccine programme. Those jabs, in contrast, are offered year after year due to waning immunity and changes in the specific viruses that are circulating.

The exact types of flu targeted by the flu vaccine are chosen each spring, depending on which strains are expected to be dominant in the coming winter period. Flu jabs used this year will be trivalent, targeting three strains of the flu virus. A form of the flu virus called B/Yamagata has not circulated since March 2020 and has been dropped from the vaccine.

Some health experts are concerned about the UK’s approach to covid-19 vaccination. Official advice not to offer boosters to unpaid carers or household contacts of immunosuppressed people has been criticised by Sheena Cruickshank, professor in biomedical sciences at the University of Manchester, writing in the Conversation.8 She also called the decision to use older vaccine doses left over from autumn 2023 in this year’s drive “enormously frustrating”, arguing that covid-19 has evolved since then and that these doses could be noticeably less effective.

In the US this year, covid-19 and flu vaccines will be available at healthcare facilities from the autumn. Everyone aged 6 months and older (with some rare exceptions) is eligible to receive these jabs, according to the US Centers for Disease Control and Prevention.9 Some people received an RSV vaccine in the US last year, but those who didn’t and who are eligible for it will be able to receive one this year.

Pharmacies are an important resource in vaccine rollouts in many European countries and the US, “because of the accessibility of pharmacies—longer hours, weekend hours, potentially no appointment [required],” says Mary Hayney, professor of pharmacy at the University of Wisconsin. “We can prevent a lot more hospital admissions with these additional vaccines,” she adds.

The European Centre for Disease Prevention and Control recommends that vulnerable and at-risk people get a flu or covid-19 jab this autumn. The advice currently remains the same as last year on that front.10 “Depending on the epidemiological situation, updated advice might be issued in upcoming months, also for RSV,” a spokesperson says.

One country approaching the end of its winter vaccination programme is South Africa, in the southern hemisphere. Health authorities there have emphasised the importance of people coming forward for flu jabs, specifically.

New vaccine tech

Cell based flu jabs—grown in the laboratory in cell cultures rather than the traditional way, in chicken eggs—will be available in Australia for the first time this year.11 Such vaccines should have fewer mutations than vaccines grown in eggs, potentially making them more effective. Cell based flu vaccines have previously been offered in the UK and US.

Japan usually offers annual flu jabs, but in 2024 its free covid-19 vaccination programme will end,12 and the government will cover perhaps only part of the cost of vaccinating people aged 65 and over as well as those who are particularly at risk of severe disease. South Korea intends to secure more than seven million doses of covid-19 vaccine,13 to be given to high risk groups this autumn and winter.

Currently, no countries are planning to include an H5N1 jab as part of widespread seasonal vaccination rollouts, but Japan will reportedly begin stockpiling these vaccines ahead of any potential pandemic.14 Earlier this year, Finland became the first country in the world to offer pre-emptive H5N1 jabs to human poultry workers.15

New vaccine strategies

Covid-19 and flu immunisations are generally given as separate injections—often at the same time, with the patient usually receiving one jab in each arm. This practice of co-administration was found to be safe in a study published in 2023.16

“We were quite happy that we saw there is no problem with reactogenicity compared to a single covid vaccination,” says coauthor Manuel Krone of the University Hospital of Würzburg. He notes that, although covid-19 has evolved since most people received their jabs in 2021 and 2022, research that he and his colleagues are currently undertaking suggests that these people still have good immune responses against the viruses. That seems to be thanks to both vaccines and previous infections, he notes. This work is yet to be published.

mRNA makes 2-in-1

Two-in-one or combined covid-19 and flu vaccinations are in development. Moderna is testing an mRNA version,17 as is Pfizer and BioNTech. “What a great idea,” says Hayney. Lindstrand agrees, though Bhatia points out that a minority of people might resist vaccination altogether if only a combined jab is available and the person in question is uncomfortable with receiving one of the two doses on offer.

One advantage of mRNA vaccines is that they can be produced very quickly. In this new world where seasonal vaccinations are becoming more numerous, the rate of production increasingly matters. “What would take weeks to months with conventional technology, with mRNA can be done in two hours—the part where you produce the ingredient,” explains Zoltán Kis at the University of Sheffield, who studies vaccine manufacturing technology. There are still challenges in that the mRNA molecule is quite fragile, he adds. And it can be more expensive to make as it requires highly purified raw materials.

Vaccines tend to be produced in batches, notes Kis, which helps regulators link any problems with vaccines in the field to their conditions of production. But continuous production of vaccines could vastly speed up manufacturing. By recording the exact time the vaccine was made, and quantifying the raw materials that went into it, continuous production could meet regulatory requirements, argues Kis. Equipment used in the process would, then, almost never be idle.

“What we see is that continuous [production] normally is around six to eightfold as productive,” says Kis. This approach might help vaccine manufacturers rapidly roll out jabs in future pandemics while maintaining capacity for seasonal vaccine production as well, he adds.

In the coming years, other diseases might be targeted by seasonal programmes. Hayney says that human metapneumovirus, another respiratory infection, is one example. It causes cold-like symptoms but can lead to hospital admissions for some people.18

Speaking generally, an annual vaccine for the “common cold”—targeting various rhinoviruses and coronaviruses known to be behind these often mild infections—would be a boon, says Bhatia. “My goodness, that would save vast hours of consultation time in general practice.”

Reflecting on the rise of various new vaccines in the 2020s and looking ahead to the coming winter, Bhatia acknowledges that annual vaccination programmes have changed drastically in just a few years. “There was a time when there wasn’t much but now there is,” he says. “That’s science for you. It’s great.”