Covid vaccines worth the gamble as odds firmly on your side

While the association between COVID vaccines and illness warrants scrutiny, there is no risk-free shot. Picture: Getty Images

AstraZeneca marketed its COVID vaccine as a public good. It took the product to market in record time and assured sceptics safety was not compromised in the process. Its approach was innovative in more ways than one. The company aimed to reduce global health inequality by ensuring supply to developing as well as developed nations. But controversy about rare instances of clotting among vaccine recipients has created anxiety and turned attention toward big pharma rival Pfizer’s mRNA vaccine.

The AstraZeneca promise was spoiled by human error, inexpert communication and defensive posturing that eroded public trust. Pfizer moved quickly into the vaccine vacuum left by AstraZeneca’s public relations disaster. The EU and Australia rushed to secure millions of doses of the Pfizer mRNA vaccine that appeared to have proven its worth in Israel.

With the L-plates off, Pfizer streaked ahead in the COVID vaccine race. But no sooner had the sun shone on the company than news broke about adverse effects. A new article in the journal Rheumatology revealed some people had developed herpes zoster shortly after receiving the Pfizer shot. Authors Victoria Furer et al noted that in the six Israeli cases, all had pre-existing autoimmune inflammatory rheumatic diseases but no previous record of shingles.

The Australian government has consistently exercised caution in response to the COVID pandemic, but its move to restrict the AstraZeneca vaccine to the over-50s seems somewhat excessive. More than 850,000 doses of the AstraZeneca vaccine have been administered locally and only three cases of the blood clotting problem known as “thrombosis with thrombocytopenia syndrome” (TTS) have been reported. To date, a causal relationship between the vaccine and TTS has not been established in Australia.

On Saturday, the Therapeutic Goods Administration said that pending further test results and an autopsy, questions remain over the death of 48-year-old NSW woman Genene Norris after she received the AstraZeneca vaccine and developed clotting. However, the TGA believes a causative link could be established in coming days.

As in other such tragic cases, Norris had pre-existing medical conditions including diabetes and photos online suggest she might have shared with many other victims a higher-than-normal body mass index.

It is not known whether she would have suffered the same devastating outcome with a different vaccine. The virus itself poses a considerable risk for the rare clotting disorder cerebral venous thrombosis — about eight times that of the AstraZeneca vaccine, according to Oxford University researchers who co-developed the AZ vaccine.

The TGA calculates the frequency of TTA in Australia at one in 295,000 and said: “The overall number of reports received for blood clots following vaccination so far has been no higher than the expected background rate for the more common type of blood clots in Australia.”

Generally speaking, experts maintain it is more beneficial to be vaccinated than face COVID unarmed. The Australian Technical Advisory Group on Immunisation has acknowledged the rarity of TTS in vaccine recipients. Studies have suggested it may occur in approximately four to six people in every one million. It noted higher rates have been reported in Germany and some Scandinavian countries. There is evidence to suggest health conditions that make people more vulnerable to COVID also predispose them to adverse vaccine reactions.

Although there is little publicly available information, a study on TTS in people who had received the Johnson & Johnson vaccine found half were obese. In March, the European Medicines Agency reported on embolic and thrombotic events associated with the AstraZeneca vaccine. There were 258 serious cases reported, with 45 fatalities. There were 30 serious cases originating from the European area. In nearly half (14) of them, “the vaccinee had risk factors for thromboembolic events such as hypertension, thyroiditis, obesity or chronic hepatitis”.

In the US, the Centres for Disease Control called for use of the Johnson & Johnson vaccine to be suspended after reporting about blood-clotting events. At the time of writing, six cases had been confirmed among more than seven million vaccinees. All of them were women and the majority had pre-existing conditions; one had asthma, one had high blood pressure and three were obese.

Companies leading the COVID vaccine race are using technological advances to elicit an immune response. AstraZeneca and the Johnson & Johnson vaccines use modified adenoviruses to deliver a gene that allows our bodies to make the pathogen’s protein. Once the body has completed the task, it should be able to recognise the specific pathogen and mount a targeted immune response rather than the immune storm seen in some COVID patients.

The Moderna and Pfizer vaccines use mRNA to instruct cells to make the spike protein found on the surface of the virus and enables our bodies to recognise it as an intruder. One problem with such vaccines is that variants of viruses can produce mutations across the spike and evade detection. The negative press about the AstraZeneca vaccine seems disproportionate given the relatively small percentage of confirmed adverse events. Overreacting to rare cases of TTS in vaccine recipients could have devastating repercussions given about 50 per cent of doses were scheduled for the global south where conspiratorial beliefs about medicine — especially Western medicine — abound.

While the association between COVID vaccines and illness warrants scrutiny, there is no risk-free shot. Vaccines are a gamble — a case of better the devil you know. But most of the time, humanity gets the upper hand.