The longer the period between a COVID-19 vaccination or infection and a subsequent booster might provide a stronger immune response.
The findings from a team at Oregon Health and Science University in the US suggest a longer period between viral exposures allows the human immune response to ‘mature’ over time.
That might mean health authorities such as the United States’ Food and Drug Administration and the Australian Technical Advisory Group on Immunisation (ATAGI), which are currently reviewing their recommended vaccination protocols, may consider lengthening the booster dose to an annual jab, as is the case for the seasonal flu vaccine.
“Longer intervals between natural infection and vaccination appear to strengthen immune response for otherwise healthy people,” says Dr Fikadu Tafesse.
The research co-led by Tafesse found robust neutralising antibody responses among some 96 health care workers with both previous infection and vaccination history.
In the case of one worker, neutralising titres – antibody counts – were especially high after 400 days. ‘Secondary boosting’ after extended intervals elicited a better immune response.
In an interview with ABC 730, Australia’s health minister Mark Butler indicated ATAGI would release advice on booster doses shortly.
“The advice to me from ATAGI was that we should expect advice from them very early this year about additional booster dose,” Butler says.
“As we move into April, May and June, and confront what the northern hemisphere is confronting right now, we need to think firstly about an additional booster dose, and ATAGI said we should expect the advice earlier this year, and need to think about additional communications campaigns to the community about the need for them.”
Boosters might improve immunity, but Australia’s vaccination rate is flatlining
While more than 90% of Australians have received the first COVID-19 vaccine protocol (two doses), less than three quarters of eligible people have had the initial booster (third) dose which became available early in 2022, and fewer than half have had last year’s ‘winter booster’.
That’s despite multiple studies finding vaccination does imbue immunity benefit.
Research published today in the Canadian Medical Association Journal found a third vaccine provided a 90% reduction in deaths among people with multiple, chronic health conditions, including diabetes and hypertension, chronic pain, kidney disease, and heart, respiratory and mental health issues.
Specifically looking at populations of Hong Kong residents receiving their boosters at the same time as the 2021 Omicron wave, the researchers suggest the mass-rollout of boosters “plausibly played a pivotal role in lowering the mortality rate amid the epidemic, especially among people living with multimorbidity.”