In Crises, Vaccines Can Be Stretched, however Not Simply

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In Crises, Vaccines Can Be Stretched, but Not Easily

In desperate times, according to experts who have done this, there are many ways to stretch vaccines and speed up vaccination campaigns.

Splitting cans, delaying second shots, injecting into the skin instead of the muscle, and using roving vaccination teams saved lives – when the circumstances were right.

For cholera outbreaks in war zones, MSF has even used a take-away vaccination, with the recipient receiving the first dose on site and the second handing them over for later self-administration.

Unfortunately, according to experts, it is currently difficult to try most of these techniques in the US, although vaccines against the coronavirus are being introduced much more slowly than hoped.

These novel strategies have worked with vaccines against yellow fever, polio, measles, cholera, and Ebola. Most of these vaccines were invented decades ago or are easier to administer because they can be given orally or stored in a typical refrigerator.

The new mRNA-based coronavirus vaccines approved to date are too fragile, experts say, and too little is known about how much immunity they confer.

The future Biden administration should focus on accelerating the production of more robust vaccines "rather than playing with current cards," said Dr. Peter J. Hotez, Dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston and the inventor of a coronavirus vaccine.

There are two strategies that could work with the current vaccines, but each is controversial.

The first is being tried in the UK. Faced with shortages and an explosive outbreak, the country's chief medical officers said in December they would be rolling out all the vaccine they had and offering modest protection to as many Britons as possible. Second doses would be delayed by up to 12 weeks and could be from a different vaccine.

There is some evidence to support the idea: early data from the first 600,000 injections in Israel suggests that just one dose of the Pfizer vaccine reduces the risk of infection by about 50 percent.

Still, some UK virologists were outraged, saying single doses could lead to vaccine-resistant strains. The Food and Drug Administration and many American vaccination scientists are also against the idea.

Moncef Slaoui, the chief scientific adviser to Operation Warp Speed, made another objection to the British plan. Single doses, he warned, could inadequately "prepare" the immune system; If those vaccine recipients were infected later, some might do worse than if they hadn't been vaccinated at all.

He recalled an incident in the 1960s when a weak new vaccine against respiratory syncytial virus, a cause of childhood pneumonia, backfired. Some children who received it and later became infected became sicker than unvaccinated children, and two young children died.

"It may only be one in 1,000 that gets an inadequate primer, but it's a problem," said Dr. Slaoui. As an alternative – the second strategy for stretching the vaccines – he suggested using half doses of the Moderna vaccine.

There is strong evidence of this, he said in a telephone interview. During Moderna's early trials, the vaccine dose of 50 micrograms produced an immune response practically identical to that of 100 micrograms.

Moderna took the higher dose as the standard to make sure it worked. Little did the company's scientists at the time know that their product would prove 95 percent effective. The higher dose would also have a longer shelf life.

However, the vaccine works better than expected, and shelf life does not matter. Therefore, Dr. Slaoui suggests using the lower dose.

"The nice thing is you inject half and get the same immune response," he said. "We hope that in a pandemic situation the F.D.A. Maybe instead of asking for a new process, you just accept it. "

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Answers to your vaccine questions

If I live in the US, when can I get the vaccine?

While the exact order of vaccine recipients may vary from state to state, most doctors and residents of long-term care facilities will come first. If you want to understand how this decision is made, this article will help.

When can I get back to normal life after the vaccination?

Life will only get back to normal when society as a whole receives enough protection against the coronavirus. Once countries approve a vaccine, they can only vaccinate a few percent of their citizens in the first few months. The unvaccinated majority remain susceptible to infection. A growing number of coronavirus vaccines show robust protection against disease. However, it is also possible for people to spread the virus without knowing they are infected because they have mild or no symptoms. Scientists don't yet know whether the vaccines will also block the transmission of the coronavirus. Even vaccinated people have to wear masks for the time being, avoid the crowds indoors and so on. Once enough people are vaccinated, it becomes very difficult for the coronavirus to find people at risk to become infected. Depending on how quickly we as a society achieve this goal, life could approach a normal state in autumn 2021.

Do I still have to wear a mask after the vaccination?

Yeah, but not forever. The two vaccines that may be approved this month clearly protect people from contracting Covid-19. However, the clinical studies that produced these results were not designed to determine whether vaccinated people could still spread the coronavirus without developing symptoms. That remains a possibility. We know that people who are naturally infected with the coronavirus can spread it while they don't have a cough or other symptoms. Researchers will study this question intensively when the vaccines are introduced. In the meantime, self-vaccinated people need to think of themselves as potential spreaders.

Will it hurt What are the side effects?

The vaccine against Pfizer and BioNTech, like other typical vaccines, is delivered as a shot in the arm. The injection is no different from the ones you received before. Tens of thousands of people have already received the vaccines, and none of them have reported serious health problems. However, some of them have experienced short-lived symptoms, including pain and flu-like symptoms that usually last a day. It's possible that after the second shot, people will have to plan to take a day off or go to school. While these experiences are not pleasant, they are a good sign: they are the result of your own immune system's encounter with the vaccine and a strong reaction that ensures lasting immunity.

Will mRNA vaccines change my genes?

No. Moderna and Pfizer vaccines use a genetic molecule to boost the immune system. This molecule, known as mRNA, is eventually destroyed by the body. The mRNA is packaged in an oily bubble that can fuse with a cell, allowing the molecule to slide inside. The cell uses the mRNA to make proteins from the coronavirus that can stimulate the immune system. At any given moment, each of our cells can contain hundreds of thousands of mRNA molecules that they produce to make their own proteins. As soon as these proteins are made, our cells use special enzymes to break down the mRNA. The mRNA molecules that our cells make can only survive a few minutes. The mRNA in vaccines is engineered to withstand the cell's enzymes a little longer, so the cells can make extra viral proteins and trigger a stronger immune response. However, the mRNA can hold for a few days at most before it is destroyed.

Many experts disagreed with the idea, including Dr. Walter A. Orenstein, associate director of the Emory Vaccine Center in Atlanta. "We need to know more before we can feel comfortable with it," he said.

"Let's stay with science," added Dr. Paul A. Offit, director of the Vaccination Education Center at Philadelphia Children's Hospital. "There are no data on the effectiveness of a partial dose."

Although Dr. Offit like Dr. Slaoui was against delaying the second dose, he expressed doubts that doing so, as the British have done, would increase the risk of poorer results in partially vaccinated patients.

Attempts in which monkeys or other animals were vaccinated and then “challenged” with intentional infection did not cause exacerbated disease, he noted. Also, the four coronaviruses that cause colds don't cause worse illness when people get them again. And people with Covid-19 don't get worse when they receive antibody treatments. generally they get better.

As is so often the case, experts disagree on how and what a new vaccine will do. Some point to hard evidence that both fractional and delayed doses have worked when doctors tried them out of desperation.

For example, yellow fever outbreaks in Brazil and the Democratic Republic of the Congo have been curbed by campaigns with just 20 percent one dose.

A shot of yellow fever vaccine, invented in the 1930s, offers lifelong protection. But a fifth of the dose can protect for a year or more, said Miriam Alia, a vaccination expert for MSF.

In 2018, nearly 25 million Brazilians, including those in Rio de Janeiro and São Paulo, faced a rapid outbreak when global offerings contained fewer than six million shots. The Brazilian government switched to a fifth of the cans and sent mobile teams to the slums to ask anyone they encountered to take them and fill in minimal paperwork. It worked: by 2019 the threat had faded.

The tactic was also used against polio. There has been a global shortage of injectable polio vaccine since 2016, and many countries use it in conjunction with the live oral vaccine. The World Health Organization has been monitoring trials in a number of ways to expand what is available.

India tried half doses first, said Deepak Kapur, chairman of Rotary International's efforts to eradicate polio in that country. Later studies showed it was possible to drop to a fifth of a dose as long as it was injected just under the skin rather than into the muscle, said Dr. Tunji Funsho, chief of polio eradication in the Nigeria chapter of Rotary International.

"That way, one vial for 10 people can reach 50 people," said Dr. Funsho.

Skin injections work better than muscle injections because the skin has far more cells that can recognize invaders and because subcutaneous layers drain into lymph nodes, which are part of the immune system, said Mark R. Prausnitz, a bio-engineer at Georgia Tech who specializes in intradermal injection techniques .

"The skin is our interface to the outside world," said Dr. Prausnitz. "Here the body expects to find pathogens."

Intradermal injection is used for vaccines against rabies and tuberculosis. Ten years ago, Sanofi introduced an intradermal flu vaccine, "but the public did not accept it," said Dr. Prausnitz.

However, intradermal injection has disadvantages. It takes more training to get right. Injectors with needle fishing devices, super-short needles, or multiple needle arrays exist, said Dr. Prausnitz, but are unusual. Ultimately, he prefers microneedle patches that are infused with dissolving vaccine.

"It would be really beneficial if we could just send these to people's homes and let them do it themselves," he said.

One major disadvantage, Dr. Slaoui, is that intradermal injection induces strong immune responses. These can be painful and bleed a little and then scrape off and leave a scar, as smallpox injections often did before the United States abandoned them in 1972.

The lipid nanoparticles in Pfizer and Moderna vaccines would be particularly susceptible to this effect, he said.

"It's not dangerous," he added. "But it's not appealing and not practical."

What the United States can and must do now, say health experts, is train more vaccines, coordinate everyone who fires the shots, and improve logistics.

Thanks to the fight against polio, measles and Ebola, some of the poorest countries in the world are routinely immunizing better than the United States currently does, said Emily Bancroft, president of Village Reach, a logistics and communications company based in Mozambique, Malawi, and the Democratic Republic Congo and support for coronavirus vaccine campaign in Seattle.

"You need an army of vaccines, people who know how to campaign, detailed micro-plans, and good data tracking," she said. "Hospitals here don't even know what they have on their shelves. For routine immunization, it's okay to get information once a month. It's not okay during an epidemic."

In 2017, the United Nations Children's Fund recruited 190,000 vaccines to deliver polio vaccines to 116 million children in one week. That same year, Nigeria injected measles vaccine into nearly five million children a week.

In rural Africa, community health workers with little formal education provided injectable contraceptives such as Depo-Provera. The basics can be taught in one to three days, Ms. Bancroft said.

Training can be performed on "injection pads" that resemble human arms. Data collection needs to be set up so that each team can report on a mobile phone and everything is routed to a national dashboard, as is currently the case in the poorest countries.

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