AstraZeneca’s Covid-19 vaccine shows one dose of the shot results in 80% less risk of death from the disease, Public Health England said on Monday. Unlike many of the vaccines, which are expensive and must be stored at very low temperatures, the Oxford–AstraZeneca vaccine can be kept in an ordinary fridge and costs a few dollars per dose. And, because it is expected to be produced on a huge scale, it could play a vital part in quelling the pandemic. It is made from a weakened version of a common cold virus (known as an adenovirus) from chimpanzees. It has been modified to contain genetic material shared by the coronavirus – although it can’t cause the illness.
Once injected, it teaches the body’s immune system how to fight the real virus.
It also said protection against death from the Pfizer-BioNTech vaccine rises from approximately 80% after one dose to 97% after two doses in its new analysis. In a study conducted by the PHE on the first protection against mortality from the AstraZeneca vaccine is based on data from a real world setting.
The study looked at new symptomatic cases of Covid-19 between December and April and people who died within 28 days of their positive test by vaccination status. People who had a single dose of AstraZeneca vaccine were 55% protected against death, with a figure of 44% protection for a single dose of Pfizer, compared to unvaccinated people.
“Combined with the protection vaccines offer against becoming a case in the first place, this is equivalent to approximately 80% protection against mortality in individuals vaccinated with a single dose of either vaccine,” PHE said in a statement.
Protection against mortality from the Pfizer-BioNTech vaccine improved to 69% for cases who had their second dose at least a week before they tested positive. Combined with the estimated protection from getting Covid-19 to start with, this is equivalent to an estimated 97% protection, PHE said.
Vaccination is recommended for persons with comorbidities that have been identified as increasing the risk of severe COVID-19, including obesity, cardiovascular disease, respiratory disease and diabetes.
Although further studies are required for persons living with HIV or auto-immune conditions or who are immunocompromised, people in this category who are part of a group recommended for vaccination may be vaccinated after receiving information and counselling.
Vaccination can be offered to people who have had COVID-19 in the past. But individuals may wish to defer their own COVID-19 vaccination for up to six months from the time of SARS-CoV-2 infection, to allow others who may need the vaccine more urgently to go first.
Vaccination can be offered to breastfeeding women if they are part of a group prioritized for vaccination. WHO does not recommend discontinuation of breastfeeding after vaccination.
Prime Minister Boris Johnson is set to confirm further easing of lockdown restrictions in England on Monday, helped in part by the speed of the country’s vaccine rollout.
In another dataset, PHE said that it was estimated that two doses of the Pfizer-BioNTech vaccine reduces the risk of hospitalisation by 93% for the over 80s. While other companies are set to make billions from their Covid vaccines, AstraZeneca is producing theirs at cost throughout the pandemic.
Unlike Pfizer and Moderna’s vaccines, the AstraZeneca jab can be stored at fridge temperature, and it will play a vital role in immunisation in low and middle income countries. After a study looking at 86 such cases in the EU, the EMA concluded the benefits of the vaccine outweighed the risk and that there was no definite causal link.
Nevertheless, Denmark has stopped its AstraZeneca rollout completely – and Germany, Spain, Italy and Ireland have suspended use of the vaccine in people under 60.
France is recommending it only be given to those aged 55 or over, while Australia says people aged under 50 should get the Pfizer jab instead.
Data from the MHRA suggests there’s a very small but slightly higher than normal incidence of a rare type of clot in younger adult age groups, particularly when the risk of being infected with coronavirus is very low, as it is now.
The risk of a clot is roughly one in 100,000 for people in their 40s, and rises to one in 60,000 for people in their 30s. Thus, based on the current data, the following is advised:
- Anyone who experiences clotting after a first dose of the vaccine should not receive a second dose
- People with a history of blood disorders (at risk of clotting) should only have the AstraZeneca when the benefits outweigh the risks
- Pregnant women should talk to their GPs about the benefits and risks
The MHRA study looked at people who had developed clots associated with a low level of platelets after receiving the Oxford-AstraZeneca vaccine.
The European Medicines Agency (EMA) has said clotting should be listed as a very rare vaccine side effect. Among these clots is a type called a Cerebral Venous Sinus Thrombosis (CSVT).
CVST occurs when a blood clot forms in large veins in the head – stopping blood from draining out of the brain.
The MHRA says anyone who has these symptoms four or more days after receiving the Oxford-AstraZeneca vaccine should seek prompt medical advice:
- A severe or persistent headache
- Blurred vision
- Chest pain
- Shortness of breath
- Swollen legs
- Persistent abdominal pain
- Unusual skin bruising
- Pinpoint spots (not including the injection site)
Covid infection itself can make clots more likely, stresses the MHRA.
However a study of around 2,000 people suggests, while the Oxford-AstraZeneca vaccine may offer more limited protection against mild and moderate disease caused by the South Africa variant, it should still protect against severe disease.
