99% of people have robust immune response against COVID-19 after one dose of Pfizer vaccine
TDS News – A new study led by Sheffield and Oxford Universities with support from the UK Coronavirus Immunology Consortium has found that 99% of people generate a robust immune response against COVID-19 after just one dose of the Pfizer vaccine.
The Protective Immunity from T cells to COVID-19 in health workers study (PITCH) examined how the immune system responds to COVID-19 after one dose of the Pfizer vaccine among people who have been infected by COVID-19 before and those who have not.
It suggests one dose of the vaccine protects against severe disease, supporting the decision to delay the second dose and provide protection to as many higher-risk groups as possible by providing more first doses. The study showed after 2 doses levels of protection were even stronger, underlining the importance of people coming forward for their second dose.
Between 9 December 2020 and 9 February 2021, researchers from the Universities of Sheffield, Oxford, Liverpool, Newcastle and Birmingham analysed blood samples from 237 healthcare workers to understand their T cell and antibody responses following vaccination from the Pfizer vaccine.
The study also sheds light on the impact of previous infection from COVID-19 on people’s immune response to vaccination. It found people who had previously been infected with COVID-19 showed higher T cell and antibody responses after one dose of the Pfizer vaccine compared with people who had never had COVID-19 before and had one dose of the vaccine.
The researchers discovered that among people who had had COVID-19 in the past, the T cell response expanded after vaccination to recognise more regions of the COVID-19 spike protein – which attacks the immune system and causes severe disease. This means, even in those already infected, vaccination from the Pfizer jab provides better protection and an enhanced immune response to COVID-19 than the immune response from natural infection.
It is not yet known how long T cell and antibody response lasts following infection. The first dose of both the Pfizer and AstraZeneca vaccine offer good levels of protection, but to get maximum protection it is vital everyone gets a second dose when invited as 2 doses of the vaccine will provide longer-lasting protection from the virus.
“The PITCH study presents further proof that vaccines provide excellent protection against the virus. Thanks to the incredible efforts of our vaccination program, over half of all adults in the UK have had the jab, and we remain on track to offer all adults a vaccine by the end of July.” Health and Social Care Secretary Matt Hancock
An effective vaccine is one that that saves lives and reduces hospitalisations. Both the Pfizer and Oxford-AstraZeneca vaccines have been shown to be highly effective in reducing COVID-19 infections among older people aged 70 years, according to previously published research carried out by Public Health England. In the over 80s, data suggest that a single dose of either vaccine is more than 80% effective at preventing hospitalisation, around 3 to 4 weeks after the jab.
Further research will continue to deepen our understanding of the immune responses over the longer term and what it means for protection against COVID-19 in the real world. Even after vaccination everyone must continue to follow the rules – remembering Hands, Face, Space – as it may still be possible to pass the virus on to others after having the jab.
A range of analyses were used to examine aspects of the T cell response including the magnitude of response and the response to different proteins from SARS-CoV-2. Carrying out these T cell analyses is much more complex than antibody studies and difficult to undertake at scale – but this study is the largest and most in depth in the world to date in this field.