Tuesday, November 24

This is how the most promising vaccines advance


A woman holds a Covid-19 vaccine.

A woman holds a Covid-19 vaccine.
Reuters

The race to find an effective and safe vaccine against covid-19 it is advancing at an unprecedented rate. The World Health Organization (WHO) draws the following picture. Currently there 200 experimental vaccines underway. 155 of these are still being tested in laboratories. 45 more are already being tested in humans. And among these, already there are 10 that are lined up in the last phase of large-scale clinical trials.

Never before in human history has something like this been accomplished. Under normal circumstances, development of a vaccine usually takes an average of 10 years. Now, however, the investigation deadlines have been compressed to less than a year. The goal, experts argue, is speed up the process without jeopardizing the effectiveness and safety of the compounds. Because yes, these injections will only achieve the green light from the health authorities if they manage to guarantee these two objectives.

The challenge of forging a formula capable of avoiding infections must deal with several obstacles before reaching the goal. On the one hand, each of the vaccines has to stand the scrutiny of large-scale clinical trials; where its effectiveness and safety is tested in thousands of patients around the world. On the other hand, it is necessary to obtain the approval of national and international regulatory bodies. And, finally, it is time to see how they are manufactured and distributed on a large scale. Experts predict that next year there could be not one, but several vaccines in circulation.

The most promising vaccines

There are currently a dozen experimental vaccines that are being tested on a large scale. On paper, the ongoing clinical trials will officially end between 2021 and 2023. But given the severity of the covid-19 pandemic around the world, pharmaceutical companies plan to request an “emergency authorization” as long as they gather minimally solid evidence on the effectiveness and safety of their formulas. This, in practice, would mean that companies could start providing the first immunizations in a matter of a few months.

Among the most advanced vaccines to date the Oxford and Astrazeneca vaccine stand out, Pfizer’s and BioNTech, Moderna, Janssen and Novavax. On the other side of the globe, the desire to find a vaccine has given the most advanced experimental vaccines a “limited approval” that allows, today, the supply of these formulas to some groups. The Chinese vaccines from Cansino, the two Sinopharm and the one from Sinovac are already being distributed among “front-line workers” such as health workers, the military and officials. Likewise, the Russian vaccines of Gamaleya and Bektop have already been patented and could soon begin to be distributed among the population.

All of the most promising formulas to date are supplied through a intravenous injection. And practically all (except the Russian) require two doses to forge a certain degree of immunity. The waiting time between the first and the second dose varies between 14 and 56 days, after which it is necessary to wait a few more weeks to consolidate the antibodies against the virus. So even when the first vaccines hit outpatient clinics, the expected ‘herd immunity’ will take a while to arrive.

When will the first vaccines arrive?

It is not yet clear when the first vaccines will arrive. The World Health Organization estimates that for the Summer of next year you can start with the vaccination of risk groups. But it will take another year, until 2022, for these injections to reach the majority of the population. This forecast collides with the dance of dates proposed by pharmaceutical companies and governments around the world. Some, the most optimistic, say that the first doses could begin to be distributed later this year. Others, more cautious, postpone the arrival of the first doses in the middle of next year.

It is also unclear who will be the first to receive a vaccine. The United Nations “strategic allocation” plan foresees the following distribution. The first to be vaccinated would be health professionals. Next, adults over 65. Then, adults with risk diseases such as cardiovascular problems, cancer, diabetes, obesity or chronic respiratory disorders. This distribution, however, will depend on the vaccine. Vaccines that have not been tested in older people, for example, cannot be provided to this group until their safety is guaranteed in clinical trials.

It will take a few 8,000 million vials of vaccine to provide at least one dose to the entire global population. To build global immunity, a total of 16 billion injections will be needed. Or more, given that we must take into account the percentage of the doses that could be spoiled along the way (15%, according to some estimates). Governments around the world, as well as international health authorities, have pledged to fight for the fair distribution of these formulas. The motto is clear. If the future vaccine against covid-19 does not reach everyone, no one will be really protected.

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