Who will get Covid-19 vaccine first

After eight months of chaos and more
than 1 million deaths worldwide, we might soon have a vaccine for the novel coronavirus. With as many as 150 vaccines in development — nearly 40 in late-stage clinical trials — it could come by the end of this year, although most experts see 2021 as more likely.
Getting a vaccine is one thing, but distributing it is another. There won’t be enough doses for everyone, at least early on, raising the delicate matter of who should get the vaccine first. Even if we agree on the goal — say, saving as many lives as possible — there may be no obvious answer. Vaccinating the most vulnerable probably makes sense for this virus, as nearly all fatalities occur in the 65-and-over age group.
Yet epidemics work in counterintuitive ways, with subtle details of how the virus or vaccine affects different people carrying huge weight. Modeling studies suggest that lots of good could also come from focusing resources on who is most likely to be spreading the virus — in this instance, younger people and children. Before we get a vaccine, we need far more research to investigate how it might be best deployed.
Experts have already developed draft guidelines for the deployment of early vaccines. An advisory group of the World Health Organization has proposed focusing on the protection of older and more vulnerable people, essential health-care workers, and groups in dense urban environments. In a report released, the US National Academies of Sciences, Engineering and Medicine offered a framework for the equitable distribution of any vaccine; it emphasizes much the same, adding to the WHO group’s list of people working in essential industries such as food and public transport.
These guidelines mostly focus on using the vaccine to protect individuals as targets of the virus, as opposed to using vaccination to slow viral transmission. But this also helps: The less prevalent the virus, the less that vulnerable people need protecting. In the right conditions, in fact, some epidemiological research suggests that vaccinating the most vulnerable may not be the right thing to do.
A modeling study published in 2009 looked at vaccination strategies for influenza and concluded that the optimal policy — considering various measures including deaths and economic costs — depended on, well, lots of things. If the vaccine was only somewhat effective, immunising only around 50% of those vaccinated, then focusing on the most vulnerable was the best strategy. With low vaccine efficacy, even vaccinating most of the population wouldn’t prevent continued viral spreading, and so the vulnerable needed direct protection.
In contrast, if a vaccine was very effective, immunising a higher proportion of those vaccinated, then the best strategy would target vaccinations not at the most vulnerable but at those most likely to spread the virus: healthy younger people, including children, who tend to be more socially active. High vaccine effectiveness makes it
possible to greatly curtail viral spread, thereby making the most vulnerable — even unprotected — far less likely to be exposed to the virus.
It also mattered within the study how many doses of the vaccine were available. With few doses available, it’s best to vaccinate the most vulnerable.
If there were enough doses to vaccinate a decent fraction of the population, then targeting the spreaders was a better idea, as
the achieved immunity level could eliminate viral spreading, although the required fraction depended on how easily the virus can be transmitted.

—Bloomberg