Why we should continue with AstraZeneca

Some countries have paused the use of AstraZeneca vaccine due to suspected cases of blood clots and low platelet counts.

So far, no causal relationship between vaccination and the events reported has been determined. Risk factors specific to the suspected very rare adverse events have not been established. What has been reported largely is an association.

An adverse event following immunisation is considered very rare if it occurs among less than 0.01 per cent of the vaccinated persons. Because an event happened after vaccination (association) does not mean that it happened because of vaccination (causality).  

Causality is a firm relationship between a cause and an effect, in which case the effect must precede the cause. The effect is what happens while the cause is why it happened.

To determine if a vaccine caused an event, receipt of the vaccine must precede the earliest manifestation of the event or demonstrate a clear exacerbation of the event. This has not been determined with the AstraZeneca vaccine.  

Vaccines like any other medical intervention such as chemotherapy, radiotherapy, surgery have adverse effects. Common adverse effects of vaccination include pain, swelling at the injection site, and fever.

Discussions surrounding safety after the introduction ofCovid-19 vaccines is not a sign of pessimism but rather hope and trust in our regulatory environment.  

It’s an assurance that the global, regional and national regulatory systems are alert and competent to deal with any safety triggers.

We should trust the judgement of our regulatory authorities with Covid-19 vaccines just as we’ve done in the past for all public health products regulation.

Contrary to misinformation, South Africa did not sell off its doses of the Astra Zeneca vaccine due to safety concerns. The vaccine wasn’t effective against the South African variant of the novel SARS Coronavirus.

African countries that purchased this consignment just like Uganda do not have the South African variant of the virus circulating on their territories.

This means that the vaccine is effective against the circulating variants of the virus in those countries just like in Uganda. However, should our surveillance systems detect the South African variant in Uganda, the use of this vaccine candidate should be re-assessed.
There’s paucity of local data to arrive at scientific conclusions based on our context.

Our involvement in clinical development should improve. It’s through participation in trials that we can determine how well a vaccine performs in our population before introduction and what safety triggers are specific to our population.

Whereas data from other geographical regions may be comparable to our setting, our best strategy should involve synthesis of local data to arrive at accurate scientific conclusions based on our context.

Public engagement to create awareness in an honest and transparent manner is very crucial now. Scientists that are qualified and competent in the field of vaccinology and infectious diseases should provide direction. Medical workers who do not have real expertise in vaccinology should never attempt to provide misleading/inaccurate information which further damages public confidence.

Vaccine from AstraZeneca is safe, effective, cheap, easy to store and transport. However, symptoms of the suspected very rare adverse events such as shortness of breath, chest pain, leg swelling, and persistent abdominal pain should be monitored and promptly treated if detected.
 
We shall overcome this pandemic if enough people become immune to the infection, and the safest means to achieve this is through vaccination.
Getting enough people vaccinated quickly has an indirect effect of protecting the unvaccinated.

This will require more than one vaccine candidate and the determination of which risk group receives what vaccine candidate will follow a clear scientific rationale.
Finally, the benefits from this vaccine outweigh any suspected risks.

Mr Ronald Opiecabo is a vaccinologist.  [email protected]