Countries that have easy access to vaccine stocks have now started giving third or booster doses of vaccine, even fourth doses, while many others are still struggling to get the first and second doses. But there is hope a new COVID-19 vaccine called CORBEVAX will help close this vaccination gap.
"About 72% of vaccine doses are administered in high- and middle-income countries, and only 1% in low-income countries," said Maureen Ferran, Associate Professor of Biology at the Rochester Institute of Technology.
How the CORBEVAX vaccine works
Ferran said all COVID-19 vaccines teach the immune system how to recognize the virus and prepare the body to attack. The CORBEVAX vaccine, is a protein subunit vaccine.
"This vaccine uses a harmless piece of spike protein from the coronavirus that causes COVID-19 to stimulate and prepare the immune system to deal with future viruses," he said.
Unlike Pfizer, Moderna, and Johnson & Johnson virus vector vaccines which give the body instructions on how to produce spike protein, CORBEVAX delivers spike protein directly to the body. Like other approved COVID-19 mRNA vaccines, CORBEVAX also requires two doses.
How was CORBEVAX developed?
CORBEVAX was developed by the co-directors of the Texas Children's Hospital Center for Vaccine Development at Baylor College of Medicine, Drs Maria Elena Bottazzi and Peter Hotez.
During the 2003 SARS outbreak, the two researchers created a similar type of vaccine by inserting the genetic information for a portion of the SARS virus spike protein into yeast to produce large amounts of the protein. After isolating the viral spike protein from yeast and adding an adjuvant that helps trigger an immune response, the vaccine is ready for use.
The first SARS epidemic was short-lived, and there was little need for the Bottazzi and Hotez vaccines. Until 2019, the deadly virus that causes COVID-19, SARS-CoV-2 emerged. Bottazzi and Hotez then cleaned up their vaccine and updated the spike protein to match SARS-CoV-2, and created the CORBEVAX vaccine.
A large US-based clinical trial found the vaccine to be safe, well tolerated and more than 90% effective in preventing symptomatic infections. The vaccine received emergency use authorization in India, and other developing countries are expected to follow suit.
Interestingly, the Baylor group was unable to raise interest or funding in the US for their vaccine. In contrast, newer technologies such as mRNA vaccines are advancing, although Bottazzi and Hotez's vaccine designs are more advanced, thanks to their previous work during the SARS outbreaks in 2003 and MERS in 2012.
Made to fill the vaccine gap
"Protein subunit vaccines have an advantage over mRNA vaccines in that they can be easily produced using well-established recombinant DNA technology that is relatively inexpensive and fairly easy to scale up," said Ferran.
Similar protein recombinant technology that has been around for 40 years has been used for the Novavax COVID-19 vaccine, which is available for use in 170 countries, and the recombinant hepatitis B vaccine.
"This vaccine can be produced on a much larger scale as the appropriate manufacturing facilities become available. Also, the key to global access is that CORBEVAX can be stored in regular refrigerators," added Ferran.
Therefore, according to him, it is possible to produce millions of doses of this vaccine quickly and distribute them with relative ease.
"In comparison, producing mRNA vaccines is more expensive and complicated because it is based on newer technology, relies on highly skilled workers and often requires very low temperatures for storage and transport," he explained.
Another major difference, Ferran continued, is that the CORBEVAX vaccine was developed with global vaccine access in mind. The goal is to make a vaccine that is inexpensive, easy to manufacture and transport using tested and safe methods.
The importance of equal distribution of vaccines
According to Ferren, there are many reasons why global access to vaccines is unfair. For example, governments of rich countries buy vaccines in advance, thereby limiting supply.
While developing countries have vaccine production capacity, low- and middle-income countries in Africa, Asia and Latin America still have to pay ordering costs.
The Indian government has ordered 300 million doses of CORBEVAX, and BioE plans to produce more than 1 billion injection doses for people in developing countries.
For context, the US and other G7 countries have pledged to donate more than 1.3 billion doses of the COVID-19 vaccine, but only 591 million doses have been delivered.
These numbers mean that if BioE is able to produce the 1.3 billion doses of CORBEVAX as planned, this vaccine will reach more people than those vaccinated against by vaccines donated and delivered by rich countries.
Ferren said the emergence of the Omicron variant should be a lesson. One of the factors for the emergence of this variant is vaccine inequality. New variants can spread worldwide rapidly and are more likely to develop in unvaccinated people and continue to emerge as long as global vaccination rates remain low.
"There is no way a booster will end this pandemic. On the contrary, developing a globally accessible vaccine like CORBEVAX is an important first step in vaccinating the world and ending this pandemic," he concluded.