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First came the good news. The European Union authorised a third vaccine. Then, the bad news. Regulators in country after country suggested restricting it to younger people until more testing was done. The decisions marked the start of a delicate new phase of vaccination drives, one in which a growing menu of coronavirus vaccines was accompanied by contentious debates about who should be given which shots. Those debates are a testament to the worlds good fortune in having several strong vaccines only a year into the pandemic. But every vaccine comes with its own idiosyncrasies, including gaps in clinical trial data. And that has thrown up agonising choices for countries already struggling to administer shots, forcing health officials to weigh their qualms about certain vaccines with the need to inoculate people before dangerous variants take hold.

After the EU authorised the AstraZeneca-Oxford vaccine last week, adding a third shot to the blocs arsenal, Germany, Italy, France, Belgium, Lithuania, Poland, Austria and Sweden all said they would restrict it to younger people or were considering doing so, citing a scarcity of data on the vaccines efficacy in older people.

Under those plans, older people would instead be scheduled to receive the Pfizer-BioNTech or Moderna vaccines, potentially leaving them unvaccinated for a period even as younger people are inoculated with the AstraZeneca shot. But those strategies, tangled as they may be, will at least make a new vaccine available to younger people, scientists said, a scenario far preferable to no one receiving AstraZenecas shot. Some scientists are now urging the United States to adopt the same approach, as the country remains without an alternative to the hard-to-store Pfizer and Moderna vaccines. Its regulators refuse to authorise AstraZenecas shot until another clinical trial generates more data, including on how it works in older people. In the absence of that data, targeting the vaccine to those in whom it is known to be effective was an urgently needed stopgap, scientists said all the more so now that the virus is rapidly acquiring new and dangerous mutations.

This is a pragmatic solution to a desperate situation, said Dr. Peter Hotez, a vaccine scientist at the National School of Tropical Medicine at Baylor College of Medicine in Texas. Everythings changed. The whole Biden plan made perfect sense up until about three to four weeks ago when we realised the pace of the variants emerging, and therefore you have to adjust. When the British scientists behind the AstraZeneca vaccine planned large-scale clinical trials in Britain and Brazil last year, they played it safe: They chose not to vaccinate older participants until they knew the vaccine was safe in younger ones, a decision that led to fewer older people being inoculated over the course of the trials. Britain, India and other countries authorised the vaccine for all adults anyway, relying on evidence that older people generate significant immune responses to the vaccine, an indicator that it will offer at least some protection. But European Union health officials have been more cautious, hewing closely to the clinical trial findings as they try to ensure that no one outside the most closely-studied groups is vaccinated. Yet, some scientists said that reserving the AstraZeneca shot for younger people would only delay injections for the people most in need of protection.

This complicates the problem, Walter Ricciardi, a professor of public health in Italy and an adviser to the Health Ministry, said of the plans.

What we need at the moment is to protect the most vulnerable people, which for sure is not the people younger than 55 years old. Confusion bubbled up in Italy after regulators there said AstraZenecas vaccine should, with some exceptions, preferably be used on adults under 55. Pfizer and Modernas shots, both mRNA vaccines that have shown roughly 95 percent efficacy in preventing Covid-19, should be given to the most vulnerable people, they said. AstraZenecas vaccine had 62 percent efficacy at two full doses in clinical trials, but it protected all participants against severe illness or death. In Italy, rumours quickly began to spread about who would receive which vaccine.

News reports suggested the AstraZeneca shot would be reserved for younger essential workers, like soldiers, teachers and janitors. But Italians spotted a hole in the plan: Some hundreds of thousands of public workers are too old to be allowed an AstraZeneca shot, but too young to qualify yet for an mRNA vaccine.

Age limits have also thrown vaccine plans into flux in Germany, where an immunisation committee authorised the AstraZeneca vaccine only for adults under 65. Given the limited supplies in Germany, those shots are likely to be reserved for younger medical workers and nursing home aides. Still, some people resisted taking AstraZenecas shot, rather than Pfizers a sign of the way people may grow choosier as more vaccines are authorised. And beyond the question of effectiveness was the matter of where the vaccines were made.

In England, the AstraZeneca shot has become known to many residents simply as the English one, making it all the more attractive. In Germany, the Pfizer shot, developed by scientists from the western city of Mainz, is spoken of with pride as the German one. Scientists have advised people to accept the first vaccine they are offered, given the widespread protections against severe disease and the societal need to tamp down the emergence of new variants. So far, countries have largely tailored vaccine offerings based on where the shots can be stored and transported. The mRNA vaccines must be kept at very cold temperatures, making it difficult to reach older people in rural areas.

The AstraZeneca vaccine, which can be stored in normal refrigerators, would be a boon to older, harder-to-reach residents. But limiting it to younger people would undo those advantages.

Britain, for its part, has achieved one of the worlds fastest vaccination programs in part by using both the AstraZeneca and Pfizer vaccines across all adults. But affections for the homegrown AstraZeneca vaccine remain strong, especially after the company published data on Tuesday suggesting that it could reduce transmission of the virus.

The writers are journalists with NYT2020

The New York Times

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The human roulette of vaccination drives - DTNEXT