Biology of Vaccines

How a Vaccine Works

There is not currently an approved vaccine for COVID-19, however, scientists around the world are working hard to find one as fast as possible with 150 in various stages of development see (Vaccine Progress).

Vaccination is the process in which substances called antigens are introduced artificially into the body to stimulate the immune system. The presence of antigens provokes an immune response, causing the body to produce antibodies which are specific to the disease and will remain in the body. Then when infected by the disease, the body will be able to respond more quickly and with fewer or less severe symptoms than would be the case if the immune system were reacting to the antigen for the first time.

Natural Immunity

Sir John Bell, Regis Professor of Medicine at Oxford University, who is leading a team to develop a vaccine said that there was likely to be a background level of protection for a lot of people.

Recent studies have shown that exposure to other coronaviruses may help the immune system when it comes to COVID-19. T-cells respond to chains of amino acids produced by different types of coronaviruses which may be why the virus is stopped in some people who never show symptoms. In older people these T-cells die off which may be why even if they have been exposed to the same coronaviruses in the past they are more susceptible to a more severe illness.

In addition, Professor Sarah Gilbert of the vaccine team said that there is evidence that people who have had COVID-19 have not developed antibodies but have developed a T-cell response which would be likely to protect them against another infection and so there may be a large number of people who have protective T cells rather than antibodies.

A German study also showed that those who only had a mild case of CoOVID-19 also had a T-cell response, suggesting that while T-cells may not stop people getting the disease it may mean they only experience mild symptoms.