Why vaccine is only a part solution

The BioNTech/Pfizer vaccine has been approved for use in the UK. This triggered President Putin to order Russian authorities to begin mass voluntary vaccinations against Covid-19. The US approval is to be granted shortly. Meanwhile Bharat Biotech’s vaccine has entered phase 3 clinical trials and manufacturing is planned of 300 million doses with the potential to increase to 500 million. All this has led to cheer that the halt to the spread of the pandemic may be near at hand. Forecasters are pointing out to China and Australia where the economy has rebounded more than expected as the spread of the virus was brought under control. The logic being promoted is that a pandemic under control will bring an economic recovery that is robust.

It is well known that as more individuals get vaccinated the remaining individuals who are not vaccinated have progressively a faint chance of becoming infected due to herd immunity.  The best strategy then when there is a risk associated with a vaccine is to have everyone else vaccinated so as to eliminate the risk of infection but for you as an individual to remain unvaccinated. This paradoxical Prisoner’s Dilemma will reduce protection for all.

Such optimism could be premature. Pfizer did not release safety information about side effects that tend to occur 6 to 8 weeks after a vaccination. It did not disclose what fraction of the volunteers who underwent trials belonged to groups who have diabetes or obesity or are over 65. This is important information as many vaccines and especially those for influenza protect younger people but are unsuccessful in safeguarding the elderly. We also do not know how long protection lasts and how often booster doses would be required. Its vaccine has to be stored at around minus 800 C and it self-destructs at high temperatures raising issues about an effective rollout.

The Russian Sputnik V vaccine is undergoing phase 3 clinical trials, including in India, and does not require to be stored at very low temperatures. Even here we have not been told how well it protects people most at risk and how long does protection from the virus last. Results for it that were reported in The Lancet showed the participants were in the age group of 18 to 60 and the trials were open label and not randomized which means we do not have the level of surety as when a trial has a placebo comparison. Side effects such as headaches and joint pain were reported in the trial participants. To the best of our knowledge nobody is releasing any safety information.

If there is a lack of trust in the perceived risks of vaccines and trust in its duration of protection then we may see less vaccination at least in some sections of society. This is not a point to be quickly disregarded.

We ought to be circumspect about the beneficial impact of the introduction of a vaccine. Historically the introduction of vaccines has resulted in sharp drops in the occurrence of a disease but the eradication of the disease has been rare. Diseases such as measles, tuberculosis, and diverse categories of influenza endure despite efforts to eradicate them. Perhaps the only vaccination that has been successful in eradication has been for smallpox. The reason for this is not because of lack of intent or resources but because of the behaviour of individuals’ response to the need for vaccination. The demand for vaccination is prevalence dependent – it is influenced by the extent of the disease. If the extent of the disease is low, then the demand is low and can even be non-existent. As this phase of reduced or no vaccination occurs the population becomes increasingly susceptible and the prevalence increases again, thus making the control of the disease increasingly intractable.

Historically the introduction of vaccines has resulted in sharp drops in the occurrence of a disease but the eradication of the disease has been rare. Diseases such as measles, tuberculosis, and diverse categories of influenza endure despite efforts to eradicate them. Perhaps the only vaccination that has been successful in eradication has been for smallpox.

The reader will immediately halt us here and remind us that the prevalence of the disease is high and so the demand for vaccination will be high and it will therefore reduce the pervasiveness of the virus. Here it is important to consider that declines in vaccine uptake occur with concerns about vaccine safety or underestimation of the risks of the disease. For instance, it has been documented that a belief that the MMR (measles-mumps-rubella) vaccine causes autism and irritable bowel syndrome generated a decline in MMR vaccine uptake in the UK. Reduced uptake of the vaccine in turn leads to higher prevalence of the disease and may result in more individuals seeking vaccination.

But if there is a lack of trust in the perceived risks of vaccines and trust in its duration of protection then we may see less vaccination at least in some sections of society. This is not a point to be quickly disregarded. The risk of meningitis/encephalitis associated with the MMR vaccination is tiny, about 1 in 1 million. The risks of infection, nonetheless, is far greater, and estimated to be 1 in 200 to 1 in 5,000 for complications due to meningitis/encephalitis after infection with measles, mumps or rubella. This can lead to sub-optimal outcomes for society as we now contend.

Pfizer did not release safety information about side effects that tend to occur 6 to 8 weeks after a vaccination. It did not disclose what fraction of the volunteers who underwent trials belonged to groups who have diabetes or obesity or are over 65. This is important information as many vaccines and especially those for influenza protect younger people but are unsuccessful in safeguarding the elderly.

It is well known that as more individuals get vaccinated the remaining individuals who are not vaccinated have progressively a faint chance of becoming infected due to herd immunity.  The best strategy then when there is a risk associated with a vaccine is to have everyone else vaccinated so as to eliminate the risk of infection but for you as an individual to remain unvaccinated. This paradoxical Prisoner’s Dilemma will reduce protection for all. As risk averse individuals seek to exploit herd immunity it makes it difficult to wipe out the virus. Such behaviour was probably behind the vaccinating conduct with regard to MMR in an advanced country such as the UK.

As long as vaccination is an individual decision which depends on the anticipated risks of a vaccine and the susceptibility to the spread of the virus, trust in the efficacy of the vaccine, its duration, and the ability of supply chains to transport in conditions so it does not lose its potency, we may see a long phase of prevalence of the virus. Outbreaks of diseases have been known to follow different patterns such as cyclical (measles is an instance), or to become irregular with time and pattern. We should be alert to this possibility and continue with public policy options such as wearing masks and personal sanitization even as vaccines are rolled out.

 

Share This -