Collective immunity to COVID-19 unlikely in 2021 despite vaccines

GENEVA – The chief scientist of the World Health Organization has warned that while many countries are starting to roll out vaccination programs to stop COVID-19, herd immunity is highly unlikely this year.

In a press conference on Monday, Dr Soumya Swaminathan said countries are critical and their populations maintain strict social distancing and other epidemic control measures for the foreseeable future. In recent weeks, Britain, the United States, France, Canada, Germany, Israel, the Netherlands and others have started vaccinating millions of their citizens against the coronavirus.

“Even if vaccines begin to protect the most vulnerable, we will not achieve any level of population immunity or herd immunity in 2021,” Swaminathan said. “Even if it happens in a few pockets, in a few countries, it won’t protect people around the world.”

Scientists generally estimate that a vaccination rate of around 70% is necessary for herd immunity, where entire populations are protected against disease. But there are concerns that the extremely infectious nature of COVID-19 requires a significantly higher threshold.

Dr Bruce Aylward, adviser to the WHO director-general, said the UN health agency was hoping coronavirus vaccinations could start later this month or in February in some of the poorest countries of the world, calling on the world community to do more to ensure that all countries. have access to vaccines.

“We cannot do it alone,” Aylward said, saying WHO needed the cooperation of vaccine manufacturers in particular to start immunizing vulnerable populations. Aylward said the WHO was aiming to have “a deployment plan” detailing which developing countries could start receiving vaccines next month.

Yet the majority of the global COVID-19 vaccine supply has already been purchased by rich countries. The UN-backed initiative known as COVAX, which aims to provide vaccines to developing countries, lacks vaccines, money and logistical support as donor countries scramble to protect their own citizens , particularly in the wake of new variants of COVID-19 detected in Britain and South Africa, which many officials blame for increased spread.

The WHO, however, said most recent spikes in transmission were due to “increased mixing of people” rather than new variants.

WHO COVID-19 technical officer Maria Van Kerkhove said the peak of cases in many countries was detected before the new variants were identified. Van Kerkhove noted that during the summer, COVID-19 cases were reduced to single digits in most countries in Europe.

“We lost the battle because we changed our mixing patterns over the summer, fall and especially around Christmas and New Years,” she said, explaining that many people had multiple contacts with family and friends while on vacation. “It has had a direct impact on the exponential growth that you have seen in many countries,” she said, calling the increase in the number of cases in some places “vertical.”

Dr Michael Ryan, WHO’s chief of emergency, said that while there is evidence that variants could accelerate the spread of COVID-19, “there is no evidence that the variants cause an element of severity. . ” He said the variants should not change countries’ strategies for controlling epidemics.

“It doesn’t change what you do, but it gives new energy to the virus,” Ryan said.

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AP medical editor Maria Cheng reported from Toronto.