Where are we with getting a COVID-19 vaccine?
This week’s expert:
Prof Nigel Crawford, Paediatrician and Head of Immunisation Services, Royal Children’s Hospital, Melbourne
Drawn from Dr David Lim’s interview with Prof Nigel Crawford on the Healthed Podcast, ‘Going Viral’.
• Currently there are many centres around the world working on developing a vaccine for COVID-19. Many of these are cooperative alliances made up of academics, biotech or pharma companies and, in some cases, government organisations. It is believed that these conglomerates – with all elements working in parallel – will expedite the large-scale manufacture and delivery of a vaccine as soon as it is proven effective and safe.
• Just recently three such centres (including the Oxford group) have had the results of their vaccine’s early phase trials published in the peer-reviewed medical literature
• A number of potential vaccines are currently going into phase III trials. Importantly many are being trialled in countries with high rates of infection eg Brazil and South Africa which will ensure that the trial will adequately test the vaccine’s effectiveness in preventing infection rather than just its ability to generate an immune response
• It is hoped some results of these phase III trials will be available by the end of 2020 and we will have products suitable for further development
• To date, it seems that people who have been infected with COVID-19 do not appear to have a sustained antibody response. However, most current antibody tests do not test for neutralising antibodies (this is only done in certain laboratories). In addition. Post-infection people may still have ‘immune memory’ even in the presence of low antibody levels, whereby an effective immune response can be mounted following re-exposure to the virus.
• It appears the SARS-CoV-2 is a fairly stable virus, slow to mutate (unlike the influenza virus for example). This is an advantage for developing a vaccine. It also means that it is less likely to become more or less virulent over time.
• Given the high infectivity of SARS-CoV-2, once an effective vaccine is available it is likely we will need vaccination rates in the order of 80% to ensure population protection.