Fourth COVID-19 shot: it’s coming for some

WITH Omicron infections soaring across the country, older Australians and other vulnerable groups will be eligible for a fourth COVID-19 vaccine from 4 April, but when will the rest of the population be able to “top-up” their immunity?

Associate Professor Nathan Bartlett, Head of Viral Immunology and Respiratory Disease Group at the University of Newcastle, said that once more vulnerable people such as the elderly have received their fourth dose, it should be rolled out to everyone else.

“There’s the impact of the disease, but also the impact on people when they (have to) stay home, he told InSight+. “People are out of commission. The impacts on the economy and all facets of life when people are off sick, is huge. School kids, teachers, you name it, any facet of our life is impacted when people across the board are being laid off due to illness

“Boosting immunity is going to reduce those impacts, it’s as simple as that.”

Federal Health Minister Greg Hunt made the announcement on Friday.

Eligible groups from 4 April are adults 65 years and over; Indigenous Australians, 50 years and over; aged care and disability residents; people aged 16 years and older who are severely immunocompromised. The extra dose can be given 4 months after the third dose, or, in people with a prior SARS-CoV-2 infection, 4 months after that infection

In the past week, the UK started vaccinating people aged 75 years and over, the immunocompromised, and care home residents with their fourth dose. Earlier in the month, Pfizer requested US emergency use authorisation for a fourth dose for older adults aged over 65 years.

In Australia, there are already some people who have received a fourth COVID-19 dose. In February, the Australian Technical Advisory Group on Immunisation (ATAGI) updated their recommendations that people aged 16 years and over who had received a three-dose primary course because of severe immunocompromise should receive a fourth dose 3 months or more after their third dose.

Similarly, children aged 5 years and over with certain conditions or on therapies leading to severe immunocompromise should receive a third primary dose of a COVID-19 vaccine.

With winter around the corner and another Omicron wave peaking in the coming weeks, should a fourth dose be recommended for more than just the elderly and immunocompromised?

The evidence is mixed.

In Israel, a fourth dose was offered to immunocompromised, older people and frontline health care workers earlier this year. They have since recommended it to all people aged over 18 years.

A study released earlier this month looked at the effect of a fourth dose of mRNA vaccines on healthy, young health workers. Although they found the vaccine was safe and somewhat efficacious (primarily against symptomatic disease), they believe a fourth vaccination for healthy, young, health care workers may have only marginal benefits. Older and vulnerable populations were not assessed in the study.

“Along with previous data showing the superiority of a third dose to a second dose, our results suggest that maximal immunogenicity of mRNA vaccines is achieved after three doses and that antibody levels can be restored by a fourth dose. Furthermore, we observed low vaccine efficacy against infections in health care workers, as well as relatively high viral loads suggesting that those who were infected were infectious,” the authors wrote.

Although the fourth dose doesn’t provide any additional protection, it does top up waning protection from the third dose which would be beneficial

However, the World Health Organization has warned against a strategy of continual boosting.

In a statement from the WHO Technical Advisory Group on COVID-19 Vaccine Composition, they wrote:

“With near- and medium-term supply of the available vaccines, the need for equity in access to vaccines across countries to achieve global public health goals, programmatic considerations including vaccine demand, and evolution of the virus, a vaccination strategy based on repeated booster doses of the original vaccine composition is unlikely to be appropriate or sustainable.”

They also encourage vaccines to be developed that can elicit mucosal immunity, in addition to systemic immunity.

Associate Professor Bartlett said those additional protections were coming.

“We will have a new generation of vaccines and complementary treatments, the treatments that will work alongside the vaccine, like the nasal spray that we’re developing. [They will] provide that other layer of protection to support the durable protection we want from our vaccines,” he said.

There’s also a focus on developing a universal vaccine which would work against not only SARS-CoV-2 but also against other coronaviruses in animal populations that may cause pandemics in the future.

It might sound like a pipe dream but Associate Professor Bartlett thinks it’s possible.

“I think there’s every reason to be optimistic. The rate at which COVID-19 first-generation vaccines were developed, manufactured, distributed – it was less than a year (and was) incredibly impressive. So, it’s clear that with concerted efforts, medical research can really generate these incredible new therapeutics with the right sort of support,” he said.

Until then, we need to be flexible and vigilant and use the resources we have available.

“All we have at our disposal are the vaccines … so they continue to be our best defence,” he concluded.