How do vaccines protect you?
The Covid vaccines reduce the risk of you becoming infected with the virus. If you do get coronavirus, vaccines mean you are very unlikely to get seriously ill, need hospital treatment or die from it.
The vaccines trigger your body’s natural production of immune cells
Covid-19 has had a huge impact on all of us. Sadly, many people have lost their lives and others have been seriously ill in hospital. Some people who have recovered, including those with mild symptoms, are still living with effects of 'long Covid' months later.
The vaccines trigger your body’s natural production of immune cells (antibodies and T cells) to protect against the Covid-19 disease. Once you have had the vaccine, your immune cells learn how to recognise and fight the virus. This means that if you get the Covid-19 virus, you already have some immunity.
Evidence has shown the vaccine reduces the virus being passed around. If you have had the jab and do get infected with coronavirus, you are less likely to spread it to friends, family and loved ones. Covid vaccines also mean you’re less likely to develop ‘long Covid’.
Do the vaccines work against new strains of the virus?
The Delta variant
The Delta variant was first identified in India and is now the biggest variant in the UK. In June 2021, an analysis by Public Health England on the Delta strain concluded the vaccines are highly effective after two doses and are likely to prevent people from becoming seriously ill and needing to be admitted to hospital.
- the Pfizer-BioNTech vaccine is 96% effective against hospitalisation after 2 doses
- the Oxford-AstraZeneca vaccine is 92% effective against hospitalisation after 2 doses
Whilst the Covid vaccines provide some level of protection against the Delta variant three weeks after the first dose, it is very important to make sure you get both doses of the vaccine to effectively protect yourself.
The Omicron variant
The Omicron variant was first identified in South Africa in November 2021. Scientists are still working to find out more information about Omicron. Data suggests that vaccine efficacy against symptomatic infection is substantially reduced against Omicron with just two doses, but a third dose boosts protection back up to over 70%.
Data suggests that vaccine efficacy against symptomatic infection is substantially reduced against Omicron with just two doses, but a third dose boosts protection back up to over 70%.
This content has been reviewed by clinicians and public health professionals
Page last reviewed: 21 December, 2021