'There are two significant advantages with these inactivated vaccines that should greatly impact our vaccine distribution program in the Philippines'
Over the past two months, we have learned that 3 COVID-19 vaccines developed in the West have successfully passed their Phase 3 clinical trials. Both of the vaccines from Moderna and Pfizer had an efficacy of around 95%, while the vaccine from AstraZeneca (AZ) had an efficacy of 62% with the standard dosing schedule that received an emergency authorization in the United Kingdom.
We have now learned that the two Chinese vaccines developed by Sinopharm and Sinovac have also passed their Phase 3 clinical trials, with an efficacy of 79% and 78%, respectively. However, details from these trials still remain unpublished at this time. (READ: China's Sinopharm says vaccine 79% effective vs coronavirus)
The two vaccines developed in China belong to a new class of COVID-19 vaccines. Both are vaccines incorporating inactivated viruses, where the intact SARS-CoV2 virus that causes COVID-19 is killed and mixed with chemicals that stimulate an immune response. The Sinopharm vaccine was tested in 60,000 volunteers from 125 countries, while the Sinovac vaccine was trialed with 12,476 individuals from Brazil. Both vaccines prevented participants from developing severe disease with complications that would hospitalize them. There were no severe side effects with either vaccine.
There are two significant advantages with these inactivated vaccines that should greatly impact our vaccine distribution program in the Philippines.
First, these vaccines can be stored in a standard refrigerator at temperatures of 2 to 8 degrees Celsius, and can remain stable for up to 3 years. This would make distribution of these vaccines in the Philippines substantially cheaper and easier as compared to the Pfizer and Moderna vaccines, which require a supercold or an ultracold chain with freezers at temperatures of -70 to -80 degrees Celsius.
Second, in principle, these inactivated vaccines should be more resilient and should be more effective against any and all SARS-CoV2 variants than the Western vaccines. Why? The Pfizer, Moderna, and AZ vaccines are composed of one part of the virus called the Spike protein. The most significant mutations in the SARS-CoV2 variants change this Spike protein, making these variants more able to escape the Western vaccines. Just a few days ago, there was a worrisome report that the South African 501.V2 variant lowers the effectiveness of antibody-based drugs against COVID-19, suggesting that this variant will lower the efficacy of the Western COVID-19 vaccines.
In contrast, these Chinese vaccines introduce the entire inactivated virus into vaccinated individuals. Novel virus variants of SARS-CoV2 would have to change everything about themselves to escape these inactivated vaccines. The probability of this happening is vanishingly small. Therefore, these vaccines would be valuable weapons against COVID-19, especially in light of the growing concerns with the B117 variant from England and the 501.V2 variant from South Africa.
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NICANOR AUSTRIACO OP
Reverend Fr. Nicanor Austriaco is Visiting Professor of Biological Sciences at the University of Santo Tomas, and an OCTA Research Fellow.