‘Unless world is vaccinated, variants will grow’: Dr Drew Weissman
Covid-19 will continue to be a problem and “variants will keep getting scarier and scarier” until at least two-thirds of the global population is vaccinated, one of the world’s foremost scientists has said, calling for efforts to minimise the inequity that has left large parts of the world without access to doses.
The comments were made by Dr Drew Weissman, professor of medicine at University of Pennsylvania’s Perelman medical school, who, along with his long-time collaborator Dr Katalin Kariko, is credited with the research that underpins the success of mRNA vaccines by Pfizer-BioNTech and Moderna.
“There are two things that have to happen for us to get the pandemic under control and stop the variants from appearing. We have to vaccinate the entire world and countries need to have a high enough percentage of people vaccinated – somewhere between 75-85% in order to reach herd immunity. Until that happens, variants will keep appearing and they are going to keep getting scarier and scarier,” he said in an interview over a video call.
The World Health Organization (WHO) said in a report on Friday that even after nearly a billion doses being given out, coronavirus vaccines remain out of reach in the poorest countries. “Over 81% have gone to high- or upper middle-income countries, while low-income countries have received just 0.3%,” WHO director-general Tedros Adhanom Ghebreyesus said during a briefing.
“The world really needs to get moving on this,” Dr Weissman said, while adding that vaccine hesitancy too needs to be tackled. “What people who are hesitant do not realise is that if they don’t take it, we are never going to reach herd immunity and Covid is going to be a problem for years and years to come,” he said.
The Penn professor also said that he expects mRNA vaccines to become cheaper over time and that he and his colleagues at the university were working on making such vaccines more stable at refrigerator temperature so that they can be moved around more easily. “All of those advances I think are going to come over the next few months,” he said.
“It (mRNA vaccines) is expensive because it’s brand new. The companies have just figured out how to make 100 million doses a month. Over time, I believe it is going to get less and less expensive.”
RNA is genetic material that human cells read to make specific proteins. For decades, scientists attempted to leverage RNA to create therapeutics. RNA allowed scientists to instruct the body to create the proteins they intended to (in the case of Covid-19 vaccines, it is the spike protein the coronavirus uses to latch onto cells).
But scientists discovered it was not easy to deliver the RNA, since the immune system recognised and destroyed it before it could enter cells and start issuing instructions. It was this problem Dr Weissman and Dr Kariko, who is also known as Kati by her colleagues, solved and reported in a paper published in August 2005.
“We spent a bunch of years studying that inflammatory activity and finally figured out how to get rid of it, which was by modifying a part of the RNA code,” Dr Weissman said, referring to what was scientifically known as a nucleoside modification.
“Kati then moved to BioNTech where she developed the LNP technology (liquid nano particles), which is also a crucial part of the Pfizer and Moderna vaccines,” Dr Weissman added. LNPs are microscopic bubbles in which the RNA of the vaccine is wrapped, helping evade the body’s natural defences till it achieves what it’s meant to do: teach a cell how to recreate the Sars-Cov-2 spike protein so that the immune system can recognise it and fight off the real virus.
The platform is also easy and quick to tweak, which will likely be an important tool to create new vaccines in case the Sars-Cov-2 mutates to become more resistant.
“The minute new variants that look concerning appear, you can take the sequence and plug it into an RNA vaccine. It will take you literally weeks to make a new vaccine. That’s because the technology is the same no matter what the sequence. (But) if you have to make an adenovirus or an inactivated virus vaccine, you have to make the virus, grow it, inactivate it — all that takes a lot of time,” Dr Weissman said
The scientist said that he and his lab are working on multiple projects to help make vaccines accessible to more parts of the country. “My lab and me personally have had a big issue with equality of vaccine access. Early last spring, we started working with the government of Thailand to build their own RNA vaccines. They are going to be able to make the vaccine in Thailand and supply it to seven surrounding LMIC. I am also working with WHO to do the same thing in Africa so that same access is available,” he said.
The professor expects some of these to become available by the end of the year.