Paris (AFP)

Will poor countries have access to a vaccine against Covid-19?

The question arises after the announcement of Pfizer and BioNTech this week on a vaccine they are developing, "90% effective".

The head of the World Health Organization (WHO), Tedros Adhanom Ghebreyesus, wished on Friday that any "scientific advance" benefits all countries: "There is no doubt that a vaccine will be an essential tool to control the pandemic".

But as richer countries plan their immunization programs until the end of 2021, experts warn of the obstacles facing poor countries.

At a cost of $ 40 per treatment - two separate injections - wealthier nations have rushed to pre-order millions of doses, before it is even known whether this vaccine will be successful.

But what about poor countries?

"If we only have the Pfizer vaccine and everyone needs two doses, it's clearly an ethical dilemma," Trudie Lang, director of the Global Health Network at Oxford University, told AFP .

There are currently more than three dozen other Covid-19 vaccines in development, 11 of which have been in phase 3 trials, the latest before approval.

Anticipating the inordinate demand for any approved vaccine, WHO created the Covax initiative in April to ensure equitable distribution.

Covax brings together governments, scientists, civil society and the private sector.

Pfizer is not one of them, but has "expressed interest in a possible supply" of Covax, however, a spokesperson for the laboratory told AFP.

- Fair sharing -

For Rachel Silverman, project manager at the Center for Global Development, it is unlikely that a significant part of the first batch of vaccines will end up in the poorest countries.

On the basis of the advance purchase agreements signed with Pfizer, she calculated that 1.1 billion doses had been purchased by rich countries.

"There isn't much left for everyone else," she told AFP.

Some countries that have pre-ordered, like Japan and Great Britain, are part of Covax, so it's likely that at least some doses will reach less developed countries through their purchasing agreements.

Conversely, the United States, which has 600 million doses on order, is not a member of Covax.

That could change with President-elect Joe Biden.

"We really have to prevent the rich countries from gobbling up all the vaccines and that there are not enough doses for the poorest countries", pleads Benjamin Schreiber, coordinator of the Covid-19 vaccine at the United Nations fund for the childhood Unicef.

In addition to ethics, epidemiological data underscore the need for equitable distribution.

Researchers at Northeastern University (United States) recently published a study examining the link between vaccine access and mortality from Covid-19.

They modeled two scenarios.

The first looks at what would happen if 50 rich countries monopolized the first two billion doses of a vaccine.

In the second, the vaccine is distributed based on a country's population rather than their ability to pay for it.

In the first hypothesis, deaths from Covid-19 would be reduced by a third (33%) worldwide.

With a fair share, the decrease reaches 61%.

- Mistrust -

But even if funding for poor countries materializes, the logistics issue will arise.

Based on a new technology, called messenger RNA, the Pfizer / BioNTech vaccine is fragile: it must be stored at -70 ° C, while "most freezers in most hospitals around the world are at -20. ° C ", notes Trudie Lang.

Pfizer and some governments have been preparing a delivery protocol for months, but "none of this has happened in low- and middle-income countries," notes Rachel Silverman.

"We have experience in deploying the vaccine against Ebola," recalls Benjamin Schreiber, a vaccine that has a profile similar to that of Pfizer in terms of storage temperature.

It is "more difficult, but not impossible," to store and administer the Covid-19 vaccine safely in the south of the world, but it would require significant investment and training, he continues.

Finally, even if several vaccines are deployed in the months to come, we will have to overcome a final obstacle: mistrust of vaccination, one of the 10 main threats to global health according to the WHO.

The Ebola vaccination in recent years has all but eradicated the virus, but several studies have shown that progress is being held back by mistrust and misinformation both online and within communities.

© 2020 AFP