Singaporeans who had smallpox jabs have fairly good mpox protection

Those born in or before 1980 would have had smallpox vaccination in childhood

- Salma Khalik

Correspondent Most older Singaporeans who were born in or before 1980 and were vaccinated against smallpox in childhood would have fairly good protection against mpox.

As smallpox and mpox are both orthopoxviruses, there is some cross-protection conferred by the vaccination.

In Singapore, vaccination against smallpox was made mandatory in 1869. This was discontinued in 1981, following a 1980 declaration by the World Health Organisation (WHO) that smallpox had been eradicated globally.

The Jynneos vaccine now given for mpox is also a vaccine used to protect against smallpox. This vaccine, third generation for smallpox, is 80 per cent effective in preventing mpox infection.

The earlier, first-generation vaccine is 95 per cent effective in protecting against smallpox, according to the Centres for Disease Control and Prevention (CDC) in the United States. Later-generation vaccines are safer.

Professor Hsu Li Yang, vicedean for Global Health at the NUS Saw Swee Hock School of Public Health, said that vaccine protection drops over time, although protection against death from smallpox will last for decades.

He said people who have had smallpox vaccination, should they get infected with mpox, are likely to have less severe symptoms.