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Covid vaccines less effective against Delta variant, study finds

The highly transmissible Delta variant now accounts for most recent Covid cases in Finland.

Ravintolan terassi täynnä väkeä Mikkelin keskustassa.
Covid infections in Finland have tripled since mid-June. The epidemic is now spreading quickly among 20 to 29-year-olds, according to health officials. Image: Juho Liukkonen / Yle

A new British study suggests that Covid vaccines are less effective in halting the spread of the Delta variant compared to other strains of the virus. All vaccines currently in use, however, protect against severe forms of the illness, regardless of the variant.

Delta now domiantes most new infections in Finland.

"This means that coronavirus measures are still necessary so that we can stop the chains of infection," said Hanna Nohynek, a chief physician at the Institute of Health and Welfare (THL).

THL guidelines mostly call for people masking up indoors unless everyone in a gathering is fully vaccinated, as inoculated people can still spread the virus to partially vaccinated and unvaccinated individuals. Nohynek emphasised that vaccinated people should wear masks at public events.

"It is a matter of concern that the Delta variant can spread more easily in partially vaccinated people than the Alpha or Wuhan strain. You should have excellent protection against becoming seriously ill after receiving two doses of the vaccine, but if unlucky, you can still pass the virus on," Nohynek explained.

She pointed to Israeli findings indicating that the Delta strain managed to break through in fully inoculated people, despite the country having vaccinated more than half of its population. In Finland, 17 people died at Kanta-Häme Central Hospital in May following an infection chain in the hospital that was attributed to Delta. A fully vaccinated hospital worker unknowingly passed the virus on to others in the ward.

The first dose of the coronavirus vaccine offers 49-percent protection against symptomatic infections caused by the Alpha variant, but only 35 percent from the Delta variant, according to the Public Health England study. The THL meanwhile claims that the second jab boosts protection against variants to between 79 and 89 percent, and up to 99 percent against the original virus.

Annual Covid jabs?

Nohynek told Yle that time will tell whether Finland introduces more Covid shots. She said decisions regarding future boosters depend on how the virus evolves.

If Finland's goal is to prevent serious illnesses and deaths and keep hospitals from being overwhelmed then, according to Nohynek, the two-shot vaccination series will do for the moment. However, if the goal is to prevent any new infections, the bar is much higher and new vaccines and more frequent doses may be needed, she explained.

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