Australians may need to receive two or even three injections of Covid each year to maintain their defenses against the virus if the first results on the effectiveness of the booster injections prove to be a useful guide.
Weekly data released just before Christmas by the UK’s Health Security Agency shows that the effectiveness of the Pfizer and Moderna boosters against symptomatic illnesses is lower for the Omicron than the Delta variant for all periods after injection.
The analysis included 147,597 Delta cases and 68,489 Omicron cases in the UK. The agency stressed that “the results should be interpreted with caution due to the low numbers and possible biases related to populations most at risk to Omicron (including travelers and their close contacts) which cannot be fully explained.”
UK data showed Pfizer and Moderna boosters to be 90% effective against symptomatic Delta variant illnesses for at least nine weeks.
In contrast, the efficacy against the Omicron strain was about 30% lower and appeared to decline further after nine weeks.
Israel has already started giving a second booster dose to keep up with the original three-dose treatment, and at least one U.S. medical center is considering recommending staff to have a second booster.
Medical experts in Australia said results beyond the 12-week data set would be needed to get a longer-term picture.
Jaya Dantas, professor of international health at Curtin University, said it was still early to understand the effectiveness of vaccinations but “it seems there may be a need for regular boosters.”
“You might need boosters, say two or three a year,” Dantas said, older people being more likely to be in line for a triple annual dose.
The virus has so far spawned 11 variants, with Delta and now Omicron being the most contagious. Ten of these strains have appeared in developing regions of the world.
“We have inequalities in vaccines,” said Dantas, the gap likely to widen as demand for a booster increases in wealthier countries. “So many parts of Africa have not even received a single dose, or they have had very low levels from a single dose.”
Michael Lydeamore, an infectious disease modeler at Monash University, said he was reassuring from the UK study that “it doesn’t matter your first two doses of vaccine – so AstraZeneca, Pfizer, or Moderna – you basically get the same protection ”from Pfizer or Moderna booster.
“It’s really important because we know AstraZeneca protection is a bit weaker initially than Pfizer’s,” said Lydeamore. “But the two hit about the same level after an encore, so that’s really good.”
As of Thursday, just over 2 million Australians had received a single booster, or 8.3% of the total population. Last week, the federal government agreed to reduce the minimum interval between the second dose and the booster from five to four months on January 4, and then to three months on January 31, making millions more eligible within weeks. future.