Covid boosters provide only limited protection against illness, new study finds

New Covid-19 boosters offer limited protection against subvariants, new research has found.

The study found that bivalent boosters, those that protect against the original Covid-19 virus and new Omicron variants, provide only slightly more protection than regular monovalent boosters.

The CDC analysed more than 360,000 health records of not-immunocompromised people 18 years old and older who were given the new boosters between 14 September and 11 November and found they protect against 40 to 60 per cent of symptomatic infections.

“This protection is not 100 per cent, but it is something,” Dr Ruth Link-Gelles, an epidemiologist at the CDC, told CNN.

Ms Link-Gelles explained that the boosters’ 90 to 100 per cent protection success was seen when they were first introduced in 2020, before dropping to 70 per cent against the Delta variant and eventually to 50 per cent against Omicron.

“And so I think what we’re seeing here is that the bivalent vaccine really brings you back to that sort of effectiveness that we would have seen immediately after past boosters, which is great. That’s where we want it to get,” she added.

Study results on the protection against death and hospitalisation have not been introduced yet.

Ms Link-Geller suggested that masks and social distancing are not a thing of the past, adding that they can be used in combination with up-to-date vaccination to obtain better results when it comes to avoiding Covid infections.

“Especially going into the holidays where you’re likely to be travelling, spending time with elderly relatives, with vulnerable people,” she told CNN. “I think having some protection from infection and therefore some protection from infecting your loved one is better than having no protection at all.”

It was also found that bivalent boosters offered 56 per cent protection eight months past the last vaccine, when there was little protection left from the previous dose.

The protection was only 30 per cent in individuals ages 18 to 49 who had gotten their last vaccine dose two to three months before the bivalent boosters, and only 28per cent for those 65 or older.

Only 11 per cent of people in the US have gotten boosters against the BA.4 and BA.5 Omicron subvariants, CNN reported.