Wednesday, September 22, 2021

Vaccines that grow on leaves and don't need needles: A look at COVID jabs you may not have heard of

You've heard of Pfizer, Moderna and AstraZeneca, but what about Medigen and Zydus Cadila?

In the race to vaccinate the world and in the face of supply issues and sanctions, some countries have developed homegrown vaccines.

There are geopolitics and vaccine nationalism at play, but the pandemic has seen a flurry of vaccine development – from the first-ever DNA vaccine to one grown on leaves.

While a lot of these vaccines sound new, the science and technologies they're built on have been around for a long time.

As ANU virologist David Tscharke notes, vaccine development is a tough business – in the past, if a vaccine already existed for a disease it was difficult to break through with a new idea.

But the pandemic has blown the field wide open.

"Nobody knew who was going to be first, nobody knew if the first one would work," Professor Tscharke said.

"So there was an enormous push into all of these really interesting vaccine technologies."

But they all basically work in the same way – telling the body to build up an immune response, so if they ever get infected with the virus, the body knows what to do.

The world's first DNA vaccine

India has often been called the pharmacy of the world, but it's not just manufacturing vaccines — it's researching and developing them too.

The homegrown vaccine from Zydus Cadila stands out for a bunch of reasons — it's the world's first DNA vaccine, and it's also needle-free. It carries the genetic code for the coronavirus spike protein, which the body can then read and generate an immune response.

The vaccine, called ZyCoV-D, was approved on August 20 and is delivered via a jet injector, sometimes called a gene gun.

It uses a high-pressure stream of fluid to blast it into the cells of the skin.

Some other DNA vaccines being developed are delivered by a patch, which is embedded with hundreds of tiny needles coated in the vaccine.

DNA vaccines don't need to be stored at low temperatures like mRNA vaccines such as Pfizer and Moderna.

ZyCoV-D has a reported efficacy of 67 per cent — lower than some other vaccines but still above the World Health Organization's 50 per cent threshold. It requires three doses.

Iran has been the worst-hit country in the Middle East and was battling a fifth wave that appeared to peak at 50,000 daily cases and 700 daily deaths last month.

In January this year, Iran's supreme leader banned the import of Pfizer and AstraZeneca, saying he didn't trust the US- and UK-made jabs.

Later, Iran did end up importing AstraZeneca that was manufactured in other countries, such as Russia or South Korea, and the new government last week approved the single-dose Johnson & Johnson.

But in the meantime, the country developed its own vaccine — COVIran Barekat — which was approved for emergency use in mid-June, before phase three trials were complete.

Early phases in clinical trials reported an efficacy of more than 90 per cent, but results have not yet been peer-reviewed.

It's an inactivated vaccine, meaning it's made by growing the virus, then killing or inactivating it. It's a similar type to China's Sinopharm vaccine — which has been the most administered in Iran.

Iran has also said US sanctions have hindered their efforts to get vaccines, but it can access them through COVAX.

"There are some countries that are under quite a lot of sanctions. So Iran is a country where it's quite difficult for them to access things depending on what the political situation is," Professor Tscharke said.

Although the US sanctions do not include medicines, in practice they have deterred international banks from financial transactions involving Iran — something that the Human Rights Watch in the past has said can have knock-on effects for Iranians' access to health care.

Taiwanese President Tsai Ing-wen made a soft-power move last month when she got her first vaccine — a home-grown variety called Medigen.

Taiwan was upheld as a poster child early on in the pandemic, keeping the virus largely under control for more than a year.

But a spike in infections in May this year highlighted the island's low vaccination rates, with only about 1 per cent vaccinated against COVID-19 at the start of that outbreak.

Taiwan refused Chinese vaccines like Sinopharm and Sinovac and instead accepted donations of AstraZeneca from Japan and Moderna from the US.

Medigen is a subunit protein vaccine, like Novavax, and its Chinese name means "high end".

The President said she wasn't nervous when she received her jab, but Medigen hasn't undergone phase three trials — due to be tested in Paraguay.

It was granted emergency approval in July amid criticism from the opposition that its approval was rushed.

Cuba has approved three vaccines for emergency use — the Abdala vaccine, Soberana 2 and single-dose Soberana Plus, and the country has another two jabs in development.

All are protein subunit vaccines, like Medigen or Novavax, and Soberana Plus can work as a booster shot.

Soberana Plus, according to the New York Times, is also tailored for those who have had COVID-19 before, in what was described as a world first.

Cuba, which is renowned for its healthcare system and has a long history of developing vaccines, has injected some national pride in its vaccine names.

Abdala is named after a poem by young revolutionary and independence hero Jose Marti, while Soberana 2 means "sovereign".

Earlier this month, Cuban authorities began inoculating toddlers as young as two years old with Soberana 2.

It has also been approved for use in Iran, while Abdala has now been approved in Vietnam.

Can vaccines grow on trees?

The majority of the world's flu vaccines are grown in chicken eggs, but Canada-based Medicago is opting for plants for its COVID-19 vaccine.

Professor Tscharke said while protein for vaccines often is grown in fermenters or vats in factories, it's possible to use a plant instead, which can be quick and inexpensive.

The idea behind this one is that it contains proteins that mimic the structure of the virus, but does not contain genetic material.

The vaccine is grown in a wild species indigenous to Australia and is related to tobacco, and the company is partially funded by cigarette maker Philip Morris International.

The plant-based vaccine is still ultimately injected, but Professor Tscharke says the broader idea of growing vaccines on plants is another platform given a push during the pandemic.

There have also been high hopes for further development of oral and edible vaccines, he said.

"People have liked the idea that you could eat your vaccines … I remember somebody who wanted to have a polio vaccine in the banana."


CDC studies show waning vaccine effectiveness against hospitalization in elderly

Covid-19 vaccines continue to work well at preventing severe disease for the vast majority of Americans but they are becoming less effective at blocking infection, according to a series of studies the Centers for Disease Control and Prevention released Friday.

Two of the analyses suggest that as the Delta variant spread this summer, the shots became less effective at keeping people 75 and older out of the hospital.

Breakthrough infections are still rare, and unvaccinated people still face significantly higher risks of illness and death from the virus. They were about 4.5 times more likely to become infected, and more than 10 times more likely to need hospitalization or die from Covid-19 than were fully vaccinated people. But the three new studies add to recent evidence that vaccines’ protection against infection ebbs over time.

CDC began last month to release the results of targeted vaccine effectiveness studies, showing protection against infection beginning to wane in residents of New York and Los Angeles and among frontline health care workers. But the agency has taken weeks to complete one of its largest and most comprehensive analyses of breakthrough infections — based on data from 13 jurisdictions with the ability to match immunization records with Covid-19 lab reports.

That study, one of the three released Friday, compared the relative risks of infection, hospitalization and death between people who are fully vaccinated and those who are not across different age groups. The CDC looked at 600,000 people infected with Covid-19 from April through mid-July. It found that overall, vaccine effectiveness against severe Covid-19 disease remains high. Incidence rate ratios for hospitalization and death changed relatively little after the Delta variant became the most dominant strain of the virus in the U.S., the study showed.

But the vaccines’ ability to prevent any infection — including mild disease — decreased from 91 percent to 78 percent after the Delta variant took over this summer.

Between April 4 and June 19, before Delta’s rise, fully vaccinated people accounted for 5 percent of cases, 7 percent of hospitalizations and 8 percent of deaths. Those figures roughly doubled between June 20 to July 17 as the variant spread. Fully vaccinated individuals accounted for 18 percent of cases, 14 percent of hospitalizations and 16 percent of deaths.

The CDC also released two reports that looked more closely at hospitalizations associated with the Delta variant and vaccine effectiveness.

One of those reports pulled on data from 1,175 patients 18 and older who were hospitalized at five Department of Veterans Affairs facilities between February and August. VA hospitals generally treat people who are older, with a higher prevalence of underlying medical conditions, than the general population.

The vaccines were 87 percent effective overall at preventing hospitalization, protection that remained relatively consistent before and after Delta became the country’s dominant variant, the study shows. But that figure masks notable differences between age groups. The shots were only 80 percent effective at keeping adults over 65 from being hospitalized with Covid, while they were 95 percent effective for people between ages 18 and 64.




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