As the Pfizer vaccine roll-out continues across New Zealand, there’s been discussion in some social media forums about whether the effectiveness of the vaccine applies equally across different ethnicities.
In Pfizer's Phase Three trial in the US, it's true that ethnic minorities were underrepresented compared to their share of the population: African-Americans made up 9.8 per cent of trial participants, lower than the 13.8 per cent census count, and Asian populations made up 4.4 per cent , lower than the census share of 5.9 per cent.
But a smaller cohort of ethnic minorities in trials does not translate to lesser effectiveness among those groups.
As of September, more than 40 per cent of the world's population has received at least one dose of vaccination for Covid-19. Pfizer's Phase Three vaccine trial included people across six countries including Turkey, South Africa, USA, Germany, Argentina and Brazil, and is approved in over 110 countries across continents.
Data shows the vaccine has been effective in reducing case growth and death rates in countries with largely non-European populations.
Singapore, which started its vaccine campaign in December 2020 using Pfizer and Moderna (another mRNA vaccine), has gone from more than 1400 daily cases in April 2020, to keeping daily cases under 40 for the majority of 2021. Even with the latest wave of community transmission in Singapore, over the past month, only about 0.2 per cent of cases required ICU care and 0.1 per cent have died.
As of September, Singapore's vaccine coverage had reached 81 per cent across its population of 76 per cent Singaporean-Chinese, 14 per cent Malay and seven per cent Indian.
In Japan, which began its Pfizer roll-out in February 2021, the case fatality rate (the number of confirmed Covid deaths among confirmed cases) has fallen steeply over the course of this year.
Saudi Arabia, where an ethnically diverse migrant population accounts for almost 40 per cent of residents, began its vaccination campaign in December 2020, using both Pfizer and AstraZeneca. As of late September, 53 per cent of its population is fully vaccinated.
Saudi Arabia's rate of death by Covid-19 reduced from 6.7 per cent in early December 2020 to 1.5 per cent in early August 2021.
One study in Israel, on multi-racial healthcare workers who'd been vaccinated with Pfizer, showed no statistically significant difference in immune responses across ethnicities.
Several immunologists Stuff spoke to said diverse ethnic representation in clinical trials is very important but so far ethnicity doesn't appear to be a strong predictor of immune response to the COVID-19 vaccines. However the immune response does vary between people and other influences such as medications, age and pre-existing conditions play a significant role.
History tells us vaccines can work effectively in different ethnicities too. Following a worldwide vaccination effort Smallpox, caused by the variola virus, was eradicated. After existing for more than 3000 years the last known case was recorded in a woman in 1977.
Vaccine expert Dr Frances Priddy told Stuff: "Underneath, our immune systems are very similar across ethnicities."
Priddy is currently leading a New Zealand clinical study into our unique population’s response to the vaccine - particularly Māori and Pasifika. Her message is that while it is important to have data on the immune responses of various ethnic groups, people shouldn’t be waiting for this data to decide on getting vaccinated - especially in a pandemic situation.
Reporting disclosure statement: This post was reviewed by The Whole Truth: Covid-19 Vaccination expert panel members Dr Maia Brewerton, a clinical immunologist, allergist and immunopathologist; and Dr Rawiri Jansen, a general practitioner and clinical director for a primary healthcare organisation.
