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As the COVID-19 Vaccine Approaches, Hope comes, but also Caution

Thousands of researchers in more than 30 countries have been collaborating and competing this year on more than 200 projects to develop a vaccine against the new coronavirus in record time.

In the most encouraging scientific breakthroughs yet, two vaccines have provided positive news that their injections were more than 90 percent effective in late-stage trials. However, several hurdles still need to be overcome, and testing that stopped at other promising candidates highlighted the uncertainties and risks developers face.

With the best hopes of ending the pandemic resting on the global deployment of an effective vaccine, the stakes are huge.

The vaccine developed by Pfizer and BioNTech showed 95 percent effectiveness, according to a final analysis of clinical trial data, while Moderna said its vaccine was 94.5 percent effective in a preliminary analysis. The results pave the way for companies to seek emergency use authorizations from regulators if more research shows the injections are also safe.

Already China and Russia have said they are using special regulatory provisions to implement domestically developed vaccines before they have undergone full testing. The use of such injections outside of clinical trials raised concern among researchers and regulators elsewhere. In an unusual public letter, nine American and European companies at the forefront of the vaccine effort pledged to avoid shortcuts in science.

The widespread use of vaccines that are not fully tested would put people who receive them at increased risk for side effects that may have been discovered in clinical trials.

The dangers were underscored in September when a volunteer in a UK trial of AstraZeneca’s experimental vaccine, developed with researchers at the University of Oxford, developed an unexplained illness. The UK trial was halted and then resumed after the company said a review recommended it was safe to do so, then AstraZeneca in October received clearance to restart a US study that had been on hold for more than a month.

In October, Johnson & Johnson also temporarily paused its study of the COVID-19 vaccine after a participant experienced an unexplained illness.

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In the 1960s, an experimental vaccine against RSV, a common respiratory virus, not only failed to protect children, it made them more susceptible. Two small children died.

Safety concerns have also arisen in the new vaccines after their approval; Thorough testing beforehand minimizes the chances of it happening. The documented reports of unexpected side effects from new vaccines are different from the persistent and incorrect belief that well-established childhood disease vaccines carry significant risks.

That myth has contributed to significant minorities of people in some countries saying they would refuse to receive a COVID vaccine. One misstep could further damage the perception of vaccines.

An inoculation must exceed a higher goal than a treatment because it is injected into healthy individuals. After testing a vaccine in animals, developers must demonstrate that it is safe and effective in humans. That usually happens in three phases, starting with testing in a small number of people aimed at achieving the strongest immune response without significant side effects. Larger-scale studies are then carried out. The final stretch, which often requires thousands of patients and lasts for years, assesses the safety and effectiveness with which a vaccine prevents infection or disease in its intended population. If a vaccine passes these tests, it must meet regulators and be produced in large quantities. The process of getting a conventional vaccine from inception to the finish line takes almost 11 years on average. The record is four years old, for the development of the mumps vaccine by Merck & Co. in 1967. Only 6 percent of experimental vaccines go to completion.

Using innovative vaccine designs, about a fifth of COVID-19 vaccine projects, including that of Pfizer-BioNTech, are based on so-called gene technology. It uses the body’s own cells to produce proteins that trick the immune system into reacting as if it had been invaded by a pathogen, training it for the real thing. These experimental vaccines can be manufactured more quickly than conventional ones, which contain an inactivated or weakened version of a pathogen, or a part of it.

Using a gene-based platform, Moderna and the U.S. National Institute of Allergy and Infectious Diseases began the first human trial of an experimental vaccine in a record 66 days after Chinese researchers made the genetic sequence of the coronavirus public. One important caveat: no gene-based vaccines have yet been licensed for humans, although some are used in veterinary medicine.

-Reduce steps. Another reason Moderna was able to move so fast was that instead of testing her vaccine on animals before switching to humans, she did both simultaneously. For COVID-19 vaccines, US and European regulators in March removed the requirement to test efficacy in animals first.

-Based on previous work. The Oxford researchers took the leap by betting on a method they have used in their ongoing work on a vaccine against the Middle East respiratory syndrome (MERS), which is caused by a related coronavirus. That vaccine appeared to be safe in early animal and human tests. The technique uses a modified cold virus as a harmless carrier to expose the immune system to the spiky protein that projects from the surface of a coronavirus like a corona, hence the name.

-Rapid regulatory monitoring. China and Russia have already done so. Guidance from the US Food and Drug Administration leaves open the possibility of an emergency use authorization for a Covid-19 vaccine. The FDA says it would require two months of safety data before reviewing any application and any submitted candidate would have to be considered by an independent panel.

Some researchers propose adopting so-called challenge trials. In the final stage of testing, researchers typically administer a vaccine to one group of volunteers and a placebo to another, then wait to see if significantly fewer in the first group develop the targeted infection. That takes time. A faster but riskier alternative is to inject volunteers with the vaccine and then deliberately expose them to the pathogen.

These challenge tests are the basis for animal studies of vaccines, and have also been used in human trials for cholera, malaria, and typhoid. Some prominent scientists have argued that the urgency of a novel coronavirus vaccine justifies its use now, and the 1daysooner.org website has compiled the names of tens of thousands of people who say they would participate. Skeptics say it is unethical to use this trial design until better and proven therapies exist to treat those who would become ill.

Despite the unprecedented mobilization, there is no guarantee that developers will offer an effective opportunity. An HIV vaccine has eluded scientists for decades, as has a single injection that would prevent all strains of flu, although researchers believe the coronavirus is an easier target because it does not appear to mutate as quickly as those viruses do. . How effective a COVID-19 vaccine could be and how long its protection would last are other crucial questions.

Given the high failure rate of experimental vaccines, developers generally do not invest in the ability to manufacture many doses before a new one looks like a winner. In this case, some of the most prominent players in the race have already expanded production facilities. Still, rolling out a new vaccine around the world is a gigantic undertaking with challenges that include sourcing the specialized glass that doses are stored in, manufacturing enough needles for injections, and ensuring vaccines are properly refrigerated throughout the supply chain. supply.

Some populations will likely receive vaccine supplies earlier than others. One risk is that wealthier nations monopolize COVID-19 vaccines, a scenario that played out in the 2009 swine flu pandemic. To prevent that, a collaboration called COVAX, led by the Coalition for Epidemic Preparedness Innovations, with Headquartered in Oslo, the World Health Organization and Gavi, a global non-profit group focused on delivering vaccines, aims to raise $ 18 billion from high- and middle-income countries. Its goal is to ensure that all poor and contributing countries have access to a proven vaccine for those most at risk, for example health workers and the elderly. Health advocates say that distributing vaccines evenly around the world isn’t just ethical. It is also essential to end the crisis. Mexico is registered in this initiative.

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