Scientists have suggested that booster shots could be used even in highly vaccinated individuals to reduce Covid transmission, particularly given the Delta variant.
There has been much debate about the pros and cons for routine booster jabs in the UK, but no decision has been made. It will likely be announced by the Guardian next week, but it could take longer.
Prof Neil Ferguson, a scientist, suggested Thursday that booster shots could be used to decrease the spread of serious illnesses and deaths, even though there is no evidence yet to show any waning protection for the double-vaccinated.
A high number of cases increases the risk for unvaccinated people or other vulnerable persons, and could result in the development of new variants.
There were more than 33,750 cases per day in the UK last week, compared to just 1,400 the previous year, before the rise in the highly infectious Delta variant. Also, before any restrictions were lifted, the number of cases was lower than the 14,000 that occurred in January. Hospitalisations and deaths in the UK are much lower than they were at peak, with nearly 80% of adults receiving two doses of vaccines.
Concerns about declining immunity have led to many rich countries with high vaccine coverage to announce the introduction of third shots.
Preliminary data suggests that people may experience a decline in antibody levels over the weeks or months following their jabs. However, this does not seem to reduce protection against serious disease or death. There is no consensus scientifically on the level of protective immunity conferred by antibodies or other tools in your immune system's arsenal.
Helen Petousis Harris, a University of Auckland vaccinologist, said boosters could be used to prevent further infections and transmission. We need these antibodies to prevent infection. If they have waned, it might be easier to establish an infection.
According to UK data, a double-vaccinated person has a half-a chance of contracting a disease than if they are unvaccinated. However, it is possible to infect others by being double-vaccinated.
Petousis Harris added that boosters can also help increase immunity to variants. People who have not responded well to primary doses of the vaccine might also benefit from boosters. These things are likely to increase immunity in the community.
Israel has, for example, already started its booster program. According to Ferguson, an epidemiologist at Imperial College London, I believe they want to reduce transmission. If you have 10% or less of your population not vaccinated, then one way to reduce risk is to increase immunity for everyone else.
The UK seems to be adopting a more incremental approach. At the moment, our joint committee on vaccines (JCVI), is only recommending boosters [third shots] to clinically extremely vulnerable individuals, which is about 1%.
Hans Kluge, head of World Health Organization Europe, suggested that booster shots be given to those who have a weak immune system and may not have reacted well to the previous two jabs.
Many scientists also stressed that rich countries should not keep vaccine supplies for third shots, while poor countries are unable to give first shots to the most vulnerable.
