The coronavirus pandemic has intriguing connections with longstanding debates about vaccination.
Vaccination proponents say it’s one of the most important public health measures of the past century, with its benefits in reducing infectious disease vastly outweighing any small risks. Critics say the benefits are overrated and that adverse effects are greater than normally acknowledged.
This was the state of play before the emergence of the new coronavirus, officially known as SARS-CoV-2. How does the coronavirus disease, Covid-19, affect the longstanding claims and counterclaims in the vaccination debate?
Quandaries for vaccination proponents
Covid-19 undermines one of the usual arguments for vaccination, namely that unless most people receive routine vaccinations, there is a possibility of a pandemic like the Spanish flu of 1918–1920 linked to the deaths of tens of millions of people. A moment’s reflection, though, should be enough to realise that vaccinating against polio and measles provides little or no protection against a new virus.
Vaccination proponents have tacitly admitted that, when a vaccine is not available, other measures may be necessary, notably contact tracing, quarantine and physical distancing along with hand-washing and other hygienic measures to reduce the risk of transmission. These are relevant for many vaccine-preventable diseases such as measles and whooping cough but are seldom emphasised, perhaps because they might detract from the importance, efficacy and efficiency of vaccination as the first line of defence.
Covid-19 has brought another possibility onto the agenda: the immunity to an infectious disease acquired by having it. This sort of acquired immunity was common before the advent of vaccines.
The entire population, referred to as the herd, is protected if enough people are immune. When, before the measles vaccine, most children had measles, this provided protection for those whose immune systems were impaired. If most people in a community have had Covid-19 then, assuming having had the disease confers immunity, the pandemic will end. However, this is likely to involve much illness and many deaths before herd immunity is attained.
Critics of vaccines have argued that there are advantages to acquiring immunity by having a disease. Before Covid-19, this argument received very little public attention.
In the vaccination debate, proponents emphasise the importance of herd immunity. This is taken to be vaccine-induced herd immunity. That is, when most people are vaccinated and most gain immunity as a result, the disease agent dies out for lack of individuals to infect.
Some commentators (including scientists) have suggested that widespread immunity acquired from having Covid-19 is an endpoint worth considering. A possible option is to allow or even encourage young and healthy people to be infected while protecting older vulnerable individuals. Few governments have adopted this option, perhaps because it clashes with the vaccination paradigm.
In summary, Covid-19 has undercut the common assumption that vaccines are the only way of dealing with infectious diseases. Claims about unvaccinated children being a health threat, and their parents being irresponsible, have been superseded by worries about contagion from coronavirus-infected individuals.
Quandaries for vaccine critics
For critics of vaccination, Covid-19 raises a possibility that might not be welcome: that an effective vaccine, if developed, might be just what is needed to bring the pandemic under control or to limit its damage. Although all vaccines pose risks, if Covid-19 is as deadly as commonly believed, even a vaccine with significant adverse effects could have more benefits than harms. This is the same sort of assessment used with other vaccine-preventable diseases.
There has been much commentary about how long it will take to test a vaccine and roll it out for the world’s population. There is no guarantee that an effective vaccine can be developed. Just as importantly, vaccines pose risks, especially when introduced for emergency purposes. Mention has been made of the vaccine for the 1976 swine flu, a vaccine that caused more harm than the flu.
Vaccine critics are already warning about the potential dangers of a coronavirus vaccine, especially one that has not received sufficient testing. Some critics see a coronavirus vaccine as a stalking horse for the introduction of mandatory vaccination, including for other vaccines. The social control measures introduced for dealing with Covid-19 might be a precursor for a different control measure: enforced vaccination despite the risks.
The public debate over vaccination is polarised: there are two sides with sharply divergent positions on benefits, risks, ethics and decision-making. This polarisation of the public debate occurs despite both sides having the same ultimate goal: protecting the health of the population, especially children. One of the effects of polarisation is to sideline other perspectives.
Proponents and critics of vaccination agree that immunity to disease is important but differ about the sorts of immunity they emphasise. Proponents focus on the benefits of vaccine-induced immunity whereas critics point to the benefits of natural immunity.
The immune system can also be boosted through various means, including exercise, diet, vitamin D, sleep and mindfulness. (For references, see my book Vaccination Panic in Australia, pages 352-355.) One of the contradictory features of the response to Covid-19 is that control measures, especially quarantine, distancing and closure of businesses, may have negative effects on an individual’s immune system.
When gyms and pools are closed and exercise classes banned, people get less exercise. In principle, people can exercise by themselves at home, and indeed are encouraged to, but for many individuals the control measures will reduce their level of physical activity. Exercise has many health benefits aside from immune system improvement.
How control measures are affecting diet is hard to determine. Closure of fast-food outlets might improve some people’s diets. On the other hand, staying at home and worrying can lead to less healthy eating.
The body manufactures vitamin D when the skin is exposed to sunlight. Staying inside reduces vitamin D production.
Ample sleep benefits people’s immune systems and general health. Staying home more of the time may be enabling people to get more sleep, though worries and physical inactivity can impair sleep quantity and quality.
Mindfulness refers to a state of mind that is calm and focused; meditation is one way to be mindful. Worrying about Covid-19, and obsessively seeking information about risks, is contrary to mindfulness. So are losing one’s job and worrying about finances.
Research shows that personal relationships are crucially important to happiness. Distancing measures have disrupted many relationships, especially physical contact, and thus have adversely impacted wellbeing. There are also other adverse impacts, including increases in domestic violence.
It is difficult to quantify the impacts of control measures on exercise, diet, vitamin D, sleep, mindfulness and relationships and hence difficult to take them into account in policy-making. Probably the impacts are more negative than positive.
One thing is certain: the vaccination debate will continue. Covid-19 may be causing some shifts in public discussions about immunity and vaccination but is incapable of ending the overall controversy.
Thanks to Tonya Agostini, Kevin Dew, Meryl Dorey, John Potterat, Jennifer Reich, Samantha Vanderslott and Jody Watts for valuable feedback on drafts. None of them necessarily agrees with any of the views in this post.