Herd immunity should be explained truthfully to the public
THERE is a lot of talk about “herd immunity” but it needs to be understood by the public so that they know what to expect from the vaccination programme and what their responsibilities are. The health authorities should also be forthcoming and educate the public that vaccination is not a magic bullet that solves everything. It has weaknesses and we have to be forever vigilant.
When a person gets a vaccination, three things are expected in exchange for the very minimal risk from the vaccination itself. Firstly, the said individual expects to be protected from contracting the disease; secondly, this protection is lifelong for certain vaccines (if they follow the schedule); and thirdly, even if the individual contracts the disease, he or she will not transmit it to vulnerable populations (like babies or cancer patients). The first two are for personal benefit and the third is a social obligation.
Most of us vaccinate our children on the basis that all three expectations will be fulfilled, but we cannot take this for granted. This is because it has been shown that in highly-vaccinated communities (post-elimination communities), immunity has been shown to be not lifelong, immunized individuals contract the disease, and immunized individuals can transmit the disease to others.
The information we have is from highly-industrialised countries which spend large sums of money on post-elimination surveillance, quickly put out any outbreaks and investigate the source of infection. We don’t know what the situation is in middle-income and poorer countries where outbreaks tend to be larger and resources are insufficient.
The term “herd immunity” apparently first appeared to be used by scientists studying infection in mice. The phenomenon is believed to have been first observed and described in humans in the 1930s by Dr Arthur W. Hedrich, a health officer in Chicago, who noted that epidemics of measles occurred when the unexposed proportion of children was around 53% and the epidemic ceased when that proportion fell to 32%. This fall in number protected the other children. However, this was with reference to natural-infection acquired “herd immunity”, as the immunity is lifelong. It also did not specifically protect vulnerable populations.
Vaccine-induced “herd immunity” poses a problem as it wanes after a while and is generally not as strong as natural immunity, as can be seen in outbreaks involving those who are fully vaccinated. And since recent research shows that fully vaccinated people can contract the disease and transmit it to others, the meaning of herd immunity in vaccinated populations becomes less clear.
Imagine a dedicated doctor working with immuno-compromised kidney transplant or cancer patients. The doctor has diligently taken his two doses of vaccination to protect his patients. At some point during his work, his immunity wanes before his next scheduled booster dose (and he is not aware of it) and he contracts an infection. Research has shown that healthy vaccinated individuals can transmit the infection to other healthy vaccinated individuals. With a ward full of unhealthy immuno-compromised patients, we can only imagine the consequences.
So, if one of the main goals of herd immunity is to protect vulnerable populations, then we may have to immunize all eligible Malaysians at regular intervals to keep immunity up. We should plan ahead for this expenditure and make the funds available.
The Health Ministry should organise road shows and town hall meetings across the country to explain the compulsory vaccination programme to parents, answer their questions and listen to their concerns.
The Health Ministry should organise road shows and town hall meetings across the country to explain the compulsory vaccination programme.