On the 10 November 2020, Pfizer and BioNTech announced their mRNA-based vaccine candidate, BNT162b2, was found to be more than 90% effective in preventing COVID-19 in participants without evidence of prior SARS-CoV-2 infection in the first interim efficacy analysis. These results are still preliminary, as the follow-up period was only for the first 7 days after the 2-doses. The vaccine also needs to be transported at -70°C to maintain the efficacy of the vaccine, which makes maintaining cold-chain a challenge.

In an interview with the Star newspaper, Prof Datuk Dr Awang Bulgiba Awang Mahmud said the storage of such a vaccine in large quantities even in big towns in Malaysia would be a challenge as -70°C freezers were not easily available. It would be even a bigger challenge for remote clinics in Sabah and Sarawak.

Then on the 17 November 2020, another biotech firm, Moderna announced their mRNA-based vaccine, mRNA-1273, was found to be almost 95% effective in preventing COVID-19. The results are based on the 95 volunteers of the 30,000 who fell ill with COVID-19. The vaccine also needs two doses, administered 28 days apart. The advantage of the Moderna vaccine over the BNT162b2 from Pfizer and BioNTech is that the vaccine only needs to be stored and transported at -20°C to maintain the efficacy.

However, both the results from Pfizer and BioNTech, and Moderna are still preliminary and still subjected to regulatory approval.

What is mRNA vaccine?

Vaccines are one of the major success stories of modern medicine. The word vaccine comes from the Latin word vaccīnus, from vacca which means cow. This is because the first modern vaccine discovery by Edward Jenner was based on the inoculation of cowpox in a 13 year-old-boy to prevent smallpox. In the 1796 experiment, Edward was able to demonstrate immunity to smallpox. From that discovery, the first smallpox vaccine was developed. It was the first step in the eradication of smallpox in 1980.

The development of vaccines has not changed much since Louis Pasteur used live attenuated cholera vaccine (1897) and inactivated anthrax vaccine (1904) in human. From there on many vaccines have been developed using either the live attenuated or inactivated route.

The conventional vaccine approaches have not been as effective against rapidly evolving pathogens like influenza or emerging disease threats such as the Ebola or Zika viruses.

RNA based vaccines could have an impact in these areas due to their shorter manufacturing times and greater effectiveness. Unlike a normal vaccine, the RNA vaccine work by the introduction of an mRNA sequence which is coded for a specific antigen. When the antigen is introduced into the body, the body immune response will produce antibodies.

The RNA vaccine are faster and cheaper to produce and is safer as they have no infectious elements.

Article written by Dr Victor CW Hoe