Vaccines don’t need to prevent transmission to protect other people
While the ideal vaccine is one that prevents both disease and transmission, the narrative that vaccines which don’t prevent transmission don’t protect other people is inaccurate and misleading. In fact, there are many vaccines predating the COVID-19 vaccines that don’t prevent transmission but still made their mark on public health.
In an article for The Conversation,
Sarah Caddy, a clinical research fellow at Cambridge University, explained that “In reality, it is actually extremely difficult to produce vaccines that stop virus infection altogether. Most vaccines that are in routine use today do not achieve this”.
She cited the example of the rotavirus vaccine:
“[V]accines targeting rotavirus, a common cause of diarrhoea in infants, are only capable of preventing severe disease. But this has still proven invaluable in controlling the virus. In the US, there has been almost 90% fewer cases of rotavirus-associated hospital visits since the vaccine was introduced in 2006.”
Another example is the pertussis vaccine, which provides protection against
whooping cough, a potentially serious illness in infants. While it doesn’t completely clear out the bacterium (
Bordetella pertussis) responsible for the disease[2], the introduction of the vaccine in the 1940s led to
a decrease in cases from more than 100,000 cases per year to fewer than 10,000 by 1965.
Natasha Crowcroft, a vaccine expert and senior technical advisor on measles and rubella for the World Health Organization,
told Scientific American that the most common flu vaccine also doesn’t prevent transmission for several reasons, such as the low immunization rate in adults and the virus’ ability to mutate rapidly. Nevertheless, depending on the year,
flu vaccines still reduce hospitalizations among older adults by an estimated 40 percent and intensive care admissions of all adults by as much as 82 percent.
