COVID-19 vaccines continue to protect against death and hospitalization worldwide while boosters can help top up immunity for vulnerable
Special interview with Professor Sir Andrew J. Pollard, FMedSci, Director of Oxford Vaccine Group and Professor of Paediatric Infection and Immunity, Department of Paediatrics, University of Oxford
It has been two and a half years since the COVID-19 virus was declared a pandemic by the World Health Organization. After multiple lockdowns, social-distancing protocols, vaccines, and debates over how to move forward and live with this virus, the world finally recognized the COVID-19 vaccines’ critical significance as a prophylactic measure against death and hospital pressures. Despite the heightened infectiousness of the new Omicron variants, infection rates have finally declined globally. However, the World Health Organization recently issued a warning: “Although reported cases and deaths are decreasing internationally, and several countries have eased restrictions, the epidemic is far from over—and it will not be over anywhere until it’s over everywhere.”
A number of world-class experts in the field of epidemic immunisation say that after the primary shots, the world population should continue to receive the COVID-19 vaccines. Professor Sir Andrew J. Pollard, Director of the Oxford Vaccine Group, expressed his thoughts on the subject:
Vaccines are highly effective against severe COVID-19 infection, and vaccinated populations with the first two primary doses had relatively few hospital admissions or deaths from the severe lung disease prevalent in the pre-vaccine period in 2020-21. However, many patients with underlying health issues or age-related frailty feel poorly with any viral disease and may require hospitalization. We now know that immunizations, while effective in avoiding severe COVID-19, are less effective in preventing infection. Boosters, on the other hand, play an essential role in preventing infection and keeping these people safe, he revealed.
New findings from Chiang Mai University in Thailand suggest that when given as a fourth dose booster on top of any previous primary or booster vaccine, the Oxford-AstraZeneca vaccine successfully prevented COVID-19 infections caused by the Omicron variants, Professor Pollard noted.
“This shows the potential of boosters to be used to top up immunity for vulnerable individuals and help defend health. We don’t yet know how best to use boosters in future years, but careful monitoring of the virus will help determine the future frequency and timing of boosters. If we can get this right, boosters will help protect people and health systems,” he said.
When asked about the trial results for Oxford-COVID-19 AZ’s vaccine, which showed overall vaccine efficacy of 70.4% versus the reported 90% efficacy of other mRNA vaccines. Professor Pollard explained that such a difference could lead to misconceptions and that viral-vector vaccines yield similar efficacy in protecting against death and severe symptoms related to COVID-19:
“Differences in licensure trial design and clinical goals make a direct comparison of trial efficacy of different vaccines tested in different nations in two very distinct studies extremely challenging. Indeed, neither research was large enough to measure the impact of severe COVID-19, the outcome that matters the most. However, we now know that both the Oxford-AstraZeneca and mRNA vaccines had a significant influence in preventing deaths and relieving demands on hospitals and health systems during the pandemic. According to a recent AirFinity estimate, the Oxford vaccine spared 6.3 million fatalities while the Pfizer vaccine averted 5.8 million deaths in their analysis of lives saved in 2021. The remarkable global reach of the Oxford-AstraZeneca vaccine, with its ease of distribution and the developers' devotion to low cost, has saved so many lives.”
“COVID-19 will be with us for decades to come, but it is difficult to be sure at the moment exactly what the future patterns of infection will look like. We don’t know how often, how big, or how long future peaks will be. Most experts think that we will need to continue to use boosters to protect the most vulnerable in society, and perhaps the virus behaves a bit like influenza with winter peaks,” he added.
The major issue is that the virus evolves quicker than we can develop and license updated vaccines. Given the recent global outbreak of Omicron variants, the following cases this year will likely to be caused by a new variant. Fortunately, the original vaccines continue to provide significant protection against severe COVID-19, and we can utilise them to protect people who require it. In the future, we anticipate that COVID-19 seasons will be more predictable, similar to flu seasons, and that we will be able to provide updated vaccines for each “season”.
“The fight against the pandemic is a complex mix of vaccine coverage and effectiveness, and timeliness. A highly effective vaccine that comes late, or doesn't reach people who need it, is no good to anyone,” he said.
The Oxford-AstraZeneca operation was successful because dosages were provided early in the pandemic, beginning in January 2021, and reached hundreds of millions of people before they were infected with COVID-19, Professor Pollard remarked.