Covid-19 pandemic: Frequent boosters can weaken immunity, says EU

Repeat booster doses every four months could eventually weaken the immune system and tire out people, it said

European Union regulators warned that frequent Covid-19 booster shots could adversely affect the immune system and may not be feasible.  

Repeat booster doses every four months could eventually weaken the immune system and tire out people, according to the European Medicines Agency. Instead, countries should leave more time between booster programs and tie them to the onset of the cold season in each hemisphere, following the blueprint set out by influenza vaccination strategies, the agency said. 

The advice comes as some countries consider the possibility of offering people second booster shots in a bid to provide further protection against surging omicron infections. Earlier this month Israel became the first nation to start administering a second booster, or fourth shot, to those over 60. The U.K. has said that boosters are providing good levels of protection and there is no need for a second booster shot at the moment, but will review data as it evolves. 

Boosters “can be done once, or maybe twice, but it’s not something that we can think should be repeated constantly,” Marco Cavaleri, the EMA head of biological health threats and vaccines strategy, said at a press briefing on Tuesday. “We need to think about how we can transition from the current pandemic setting to a more endemic setting.”

The EU regulator also said at the briefing that oral and intravenous antivirals, such as Paxlovid and Remdesivir, maintain their efficacy against omicron. The agency said that April is the soonest it could approve a new vaccine targeting a specific variant, as the process  takes about three to four months. Some of the world’s largest vaccine-makers have said they are looking at producing vaccines that could target new variants. 

Omicron overtaking Delta globally in terms of circulation: WHO

Omicron is quickly overtaking the Delta variant of Covid-19 and becoming dominant around the world, a senior WHO official has warned, with the global health agency cautioning that there is "increasing evidence" Omicron is able to evade immunity but has less disease severity as compared to other variants.

It could take some time for Omicron to overtake Delta in some countries, because it depends on the level of circulation of the Delta variant in those countries, Infectious Disease Epidemiologist and Covid-19 Technical Lead at the World Health Organisation (WHO) Maria Van Kerkhove said on Tuesday.

“Omicron has been detected in all countries where we have good sequencing and it's likely to be in all countries around the world. It is quickly, in terms of its circulation, overtaking Delta. And so Omicron is becoming the dominant variant that is being detected,” Kerkhove said during a virtual questions and answers session.

She further cautioned that even though there is some information that Omicron causes less severe disease than Delta, “it's not a mild disease” because “people are still being hospitalized for Omicron.” The Covid-19 Weekly Epidemiological Update, released by the WHO, said that over 15 million new Covi-19 cases were reported globally in the week of January 3-9, a 55 per cent increase as compared to the previous week when about 9.5 million cases were reported.

Over 43,000 new deaths were reported in the past week. As of 9 January, over 304 million confirmed COVD-19 cases and over 5.4 million deaths have been reported.

The highest numbers of new cases were reported from the US (4,610,359 new cases; a 73 per cent increase), France (1,597,203 new cases; a 46 per cent increase), the UK (1,217,258 new cases; a 10 per cent increase), Italy (1,014,358 new cases; a 57 per cent increase) and India (638,872 new cases; a 524 per cent increase), the update said.

Kerkhove said the 15 million cases reported in the last seven days are a “record high in this pandemic” and are an “underestimate” given the challenges in surveillance around the world and COVID-19 self-tests at home that are not registered.

The WHO update said that the Omicron variant has a substantial growth advantage and is rapidly replacing other variants.

“This variant has been shown to have a shorter doubling time as compared to previous variants, with transmission occurring even amongst those vaccinated or with a history of prior SARS-CoV-2 infection; there is increasing evidence that this variant is able to evade immunity,” the update said.

It said that in terms of disease severity, there is growing evidence that the Omicron variant is less severe as compared to other variants.