Severe infection outcomes can be prevented for those who receive COVID-19 vaccine

We thank Mr Lim Teck Koon for his letter (Clarify the truth about the efficacy of COVID-19 vaccines, 1 May)

Any vaccine authorised for use in Singapore must be assessed for high safety and efficacy standards, and COVID-19 vaccines currently in use here have shown high efficacy rates of about 95%. For the vast majority of those vaccinated, the COVID-19 vaccine is effective in preventing symptomatic disease. Nevertheless, a small number of vaccinated individuals may still develop disease, although such occurrences are currently assessed to be uncommon.

Firstly, a vaccinated individual can still develop COVID-19 if they are exposed to a very large amount of the virus. Vaccination is an important tool to help lower the risk of infection and severe disease, but it does not eliminate the risk completely. This is why vaccination should be taken in tandem with existing public health and safe management measures such as mask-wearing and good personal hygiene, to reduce the risk of transmission of COVID-19.

Secondly, another concern about the reduced effectiveness of vaccines is the emergence of variants. The COVID-19 vaccines from Pfizer-BioNTech and Moderna used in Singapore currently have been shown to be effective against the original SARS-CoV-2 virus and some variants such as the B1.1.7 strain, although efficacy against other new strains may be lower. More data on this is being studied. While protection conferred against new strains may be lower, an unvaccinated person would have no protection against COVID-19 at all.

Personal health factors can contribute to the risk of infection and severe disease from COVID-19, and persons with chronic diseases are at risk of more severe disease from COVID-19 infection. Vaccination has been shown in clinical trials to be equally efficacious in persons with chronic diseases, and it is recommended for them to be vaccinated.

We strongly encourage all who are medically eligible to be vaccinated when the vaccine is offered to you, to keep our loved ones and those in the community safe.

Vernon Lee (Associate Professor)

Director, Communicable Diseases Division

Ministry of Health