Covid, if many months pass between illness and vaccination booster, the immune response will be stronger –

Of Silvia Turin

The amount of antibodies obtained with hybrid immunity was measured: infection plus subsequent vaccination (but also the opposite). Better results the more time passes between the two moments, up to a year. Indication for vaccination campaigns

A new study has monitored what thebest time frame (more protective) between a Covid infection and a subsequent booster vaccination and found that immunity is stronger how much longer the period which separates the two moments. The longest interval measured in the study was 404 days.

How and when better antibodies are developed

The research, conducted by the Oregon University of Health and Science (OHSU) and published in the Journal for Clinical Investigation Insight
, wanted to deepen this knowledge to give scientific material to the decision-makers of the next vaccination campaigns. In this study – reads the summary written by the team of scientists -, we explore the impact of the combination of vaccination and infection, also known as “hybrid immune”, and its timeline on the quality and quantity of antibodies elicited in a cohort of 96 health workers. Neutralizing antibody responses against all variants (including Omicron BA.2) were robust and neutralizing titres significantly improved when intervals between infection and vaccine were longer, in direct proportion: the immune response was uniformly faster the stronger the longer the period of time between the two moments (even reaching more than a year, in fact). This effect was found even when there was a vaccination before and later a reinfection.

The immune system learns little by little

Scholars’ findings suggest that the extent, potency, and breadth of the hybrid immune response they all increased with a longer period of time between exposures to the virus (either through vaccination or through natural infection). This probably related to the fact that the body’s immune response matures over timesaid co-senior author Marcel Curlin, an associate professor of medicine at the OHSU School of Medicine: The immune system is learning, he said.
The findings could extend to vaccine booster doses, an important consideration for future vaccine campaign strategies, although, in this case, the immune response was measured in healthy people (boosters could be recommended on a more frequent basis between vulnerable, elderly or immunocompromised people).

Annual recalls?

Currently in Italy vaccination boosters are recommended from 120 days after infection or another vaccine dose, but for healthy people it could be considered whether to extend this minimum time.
A committee of advisers from the Food and Drug Administration (FDA) just met last week to start setting up the future of the vaccination campaign in the USA. The committee screened (but did not vote on) the proposals to make i annual vaccination boosters, just like the flu, probably in the fall and possibly with up-to-date vaccines. The idea behind it is to make vaccination less complicated and confusing, with the ultimate goal of getting more people vaccinated, no matter how many doses they have already received. The agency will meet again on the same issue in late May or early June this year to get vaccines ready for fall. Older people, young children, and people with compromised immune systems may be offered multiple vaccination appointments that are less spaced apart.

February 1, 2023 (change February 1, 2023 | 11:00 am)


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