Oxford/AstraZeneca vaccine delays could cause thousands of additional deaths

Delays in the deployment of the Oxford/AstraZeneca vaccine due to blood clot fears are likely to result in thousands of excess deaths, a new mathematical study has shown.

Researchers used statistical analysis to predict excess deaths in the absence of a vaccination programme in Italy and France – both of which paused the roll-out of the Oxford vaccine in March –compared with deaths expected due to blood clotting as a now-confirmed rare side effect.

The study, published in April 2021, estimated that suspending the Oxford vaccine for a week without offering an alternative would lead to almost 800 additional deaths in Italy and 160 in France. Pausing vaccinations for a month was estimated to result in around 3,000 deaths in Italy and 700 in France.

Professor Valerio Lucarini, a statistical mechanics mathematician at the University of Reading and co-author of the study, said: “Assuming the entire populations of the countries we looked at were vaccinated with the Oxford/AstraZeneca vaccine, the average fatality rate from blood clots and the number of cases seen suggests there would be about one excess death a month due to blood clots, some of which might have occurred anyway.

“When you consider that not delivering the vaccines is predicted to result in hundreds if not thousands of deaths due to the coronavirus continuing to spread, this data backs up the claim that the benefits of the Oxford jab outweigh the risks.

“This research demonstrates the real-world application of mathematics to help make decisions that influence public health, and even save lives.”

A small number of suspicious cases of deep vein thrombosis have been reported in Europe following the Oxford/AstraZeneca vaccine. This led to the European Medicines Agency and Medicines and UK’s Healthcare products Regulatory Agency to advise in April that unusual blood clots with low blood platelets should be listed as a very rare side effect, but that the vaccine was still safe.

The new research was led by the Laboratoire des Sciences du Climat et de l’Environment and is published in the journal Chaos. The estimates were based on the R rates in Italy and France at the start of the spring, and analysis of publicly available data on Covid-19 infections and excess deaths.

They used the lowest estimated efficacy value of a single shot of the Oxford vaccine, and assumed the rate of vaccinations would not increase.

It was predicted that vaccinating the entire populations of Italy and France with the Oxford vaccine would result in around 13 deaths in Italy and 15 in France, based on the average fatality rate for deep vein thrombosis.

The worst case scenario estimates for blood clotting deaths due to the Oxford vaccine, which assumes a 100% fatality rate, were around 280 in Italy and 300 in France. This was a similar number (around 260) to the excess deaths predicted for Italy due to just a three-day pause in vaccinations.