Booster effectiveness waning after 4 months

Pharma News: The recent report released by the Centre for Disease Control (CDC) reveals how our immunity can wane after receiving a booster jab against COVID-19.

The CDC says that during the Omicron-predominant period, vaccine effectiveness against COVID-19–associated ED or urgent care visits and hospitalisations was 87% and 91%, respectively, during the two months after a third dose. However, it decreased to 66% and 78% by the fourth month after a third dose.

Dr Daniel Layton, immunologist from the CSIRO, commented “While a number of countries have authorised the use of a second booster shot, there is currently limited clinical data on whether it will provide increased effectiveness. Our immune system is regularly being challenged by viruses and bacteria around us, often mounting an immune response to multiple pathogens each year. It is unlikely that additional boosters will have negative impacts on our immune system, however advisory groups such as ATAGI will be closely monitoring emerging data to determine what benefit is to be gained from additional boosters.

“The data presented by the CDC actually shows how effective our current vaccines are, even against the Omicron variant, particularly in the first 2-3 months following the booster.”

Associate Professor Sanjaya Senanayake, a specialist in Infectious Diseases and Associate Professor of Medicine at The Australian National University, added “Regarding fourth or extra doses, especially if it is not an Omicron-specific vaccine, it may be prudent to target vulnerable populations, such as the elderly, immunocompromised and those with certain risk factors. While Australia has demonstrated good vaccine uptake to this point, ‘vaccine fatigue’ might kick in, especially in younger people.

“In terms of the vaccine landscape, there are eight intranasal (literally sprayed up the nose) vaccines that are in various stages of clinical trials. These vaccines may be more effective at providing robust immunity in the nasopharynx itself and therefore make it harder for a recipient to get infected and transmit the virus. Other vaccines such as the Spike Ferritin Nanoparticle vaccine from the US might offer broad immunity against multiple variants.

“And it is here that the danger with COVID-19 arises, since a new variant may reset the immunity clock once again. And there is no guarantee that a future variant will not be more virulent than Omicron.”

Dr Deborah Cromer, Group Leader in Infection Epidemiology and Policy Analytics and a Senior Research Fellow in the Infection Analytics Program at The Kirby Institute, University of New South Wales, said “This latest report adds to the accumulating weight of evidence that supports the idea that COVID-19 will become an endemic disease in the population, with continued immune boosting either from natural infection or annual vaccination being required to maintain protection.”