Sometimes it is worth stating the obvious: ‘The development of safe and highly effective vaccines during the latter half of the 20th century has been one of medicine's greatest achievements … Collectively, traditional vaccines are estimated to save approximately 4–5 million lives per year’ (Malhotra, 2022).
But mistakes can be made in any field of human endeavour, including vaccine development. For example, in 1953 the first human pilot studies of a formalin-inactivated poliovirus vaccine were undertaken; and 1954 saw 1.8 million children in the US, Canada and Finland receive this vaccine in the world's largest clinical trial. However, in 1955, after mass polio vaccination began in the US, 250 cases of atypical paralytic poliomyelitis occurred after the Cutter and Wyeth pharmaceutical companies each released polio vaccine that had been inadequately inactivated (Juskewitch et al, 2010).
More recently, in 2015, the Philippine Food and Drug Administration approved Dengvaxia, an attenuated yellow fever virus that expresses genes of each of the four types of dengue virus; in 2017 the vaccine was withdrawn because of safety concerns over vaccine-induced enhancement; and in September 2018 it was revealed that 130 vaccinated children had died (Arkin, 2019).
In April this year, a different perspective on vaccine safety was aired by Stabell Benn et al (2023), who note that our present-day protocols for the testing and regulation of vaccines were established ‘before the realisation that vaccines, in addition to their effect against the vaccine-specific disease, may also have “non-specific effects” affecting the risk of unrelated diseases.’
They cite, for instance, historical anecdotal evidence from Calmette, co-inventor of the Bacillus Calmette-Guérin (BCG) vaccine, that mortality was reduced by 75% among BCG-vaccinated children in Paris, more than could be explained by tuberculosis prevention: ‘He speculated that the vaccine may have additional benefits, strengthening the general resistance against other infections.’ In the 1960s and 1970s, Russian researchers who undertook ‘large trials of live enteroviruses, including oral polio vaccine … found that they significantly reduced the risk of influenza infection’ (Stabell Benn et al, 2023).
Conversely, some non-live vaccines, while protective against the vaccine's target infection, might increase the risk of contracting other infections, especially in females, under certain conditions. For example, in low-income settings, females given a non-live diphtheria-tetanus-pertussis (DTP) vaccine ‘have a 1.5–2 times higher mortality rate than female individuals who have not received the vaccine and a similar increased risk above that of male individuals vaccinated with DTP’ (Stabell Benn et al, 2023).
Given this context, it is intriguing that Noé et al (2023) reported, following an albeit small study of 29 children given Pfizer's BNT162b2 Covid-19 vaccine, that one of their main findings was that ‘BNT162b2 vaccination alters heterologous bacterial and viral cytokine responses 28 and 182 days after the primary vaccination schedule, compared to pre-vaccination …’
Malhotra (2022), while acknowledging the undoubted success of many vaccination campaigns over several decades, has expressed concern over aspects of Covid-19 vaccination, and Demasi (2022) points out: ‘In July 2021 the US Food and Drug Administration quietly disclosed findings of a potential increase in four types of serious adverse events in elderly people who had had Pfizer's Covid-19 vaccine: acute myocardial infarction, disseminated intravascular coagulation, immune thrombocytopenia, and pulmonary embolism.’
Raising such concerns is a matter of exercising appropriate scientific rigour; it is not about being unduly alarmist. Stabell Benn et al (2023) are justified in asserting that the framework for ‘testing, approving, and regulating vaccines needs to be updated to accommodate non-specific effects’ and that at present vaccines are not being tested optimally. They raise a valid issue that is worthy of debate.
However, perhaps the most important point made by Stabell Benn et al (2023) is that some might fear their proposed changes ‘may open the door to an unwarranted discussion of vaccine safety, therefore strengthening the anti-vaccination movement.’
To which they respond – correctly – by suggesting that ‘in our view, it would be devastating if the anti-vaccination movement were given this type of power to define, and possibly restrict, the use of a sound scientific method …’
It is unacceptable to label someone as an ‘anti-vaxxer’ because they voice concerns in the context of a scientific debate where evidence is discussed and evaluated; not where dogma is asserted to the exclusion of reason.