AstraZeneca and Oxford University's COVID-19 vaccine is more effective when its second dose is given three months after the first, instead of six weeks, a peer-reviewed study 

The study confirmed the Anglo-Swedish drugmaker's findings from earlier this month that showed the vaccine had 76 per cent efficacy against symptomatic coronavirus infection for three months after the first dose.

Efficacy was found to be at 81 per cent&nbsp;with the longer interval of 12 weeks between the first and second dose, compared with 55 per cent&nbsp;efficacy up to the six-week gap, according to the Lancet study, which backs British and World Health Organizations&nbsp;recommendations for longer intervals.&nbsp;

Canada has not yet approved the&nbsp;AstraZeneca-Oxford shot, but is 

COVID-19 vaccine deliveries back on track following weeks of delay, says Public Health Agency

Deliveries of COVID-19 vaccine doses from two approved vaccine makers — Pfizer-BioNTech and Moderna — are back on track following weeks of reduced shipments, officials from the Public Health Agency of Canada said today.

A health-care worker prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at a UHN COVID-19 vaccine clinic in Toronto on Thursday, January 7, 2021.

COVID Ont Vaccine 20210107

A health-care worker prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at a vaccine clinic in Toronto in January. The Public Health Agency of Canada says deliveries of COVID-19 vaccine doses from the two approved vaccine makers are back on track following months of delays.

Faced with a resurgence in infections and new, highly transmissible variants of the virus, many countries are hoping to broaden immunization by giving some protection to as many people as possible with a first dose, while delaying subsequent shots.&nbsp;

"Vaccine supply is likely to be limited, at least in the short term, and so policy-makers must decide how best to deliver doses to achieve the greatest public health benefit," said the study's lead author, Andrew Pollard, who is with Oxford, in a statement provided by The Lancet.

Pfizer says variant identified in South Africa could result in fewer protective antibodies

A laboratory study suggests that the variant of the coronavirus first identified in South Africa may reduce protective antibodies elicited by the Pfizer-BioNTech vaccine by two-thirds, and it is not clear if the shot will be effective against the mutation, the companies said on Wednesday.

A health-care worker prepares a dose of the Pfizer-BioNTech vaccine against COVID-19 during the first stage of the vaccination campaign at Clínica Colombia on February 18, 2021 in Bogota, Colombia. The first batch of 50,000 doses of the Pfizer-BioNtech vaccine against COVID-19 intended to be distributed among first line health workers, according to the Colombian Health Ministry. 

Pfizer-BioNtech vaccine against COVID-19

A health-care worker prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at a clinic in Toronto in January.

"Where there is a limited supply, policies of initially vaccinating more people with a single dose may provide greater immediate population protection than vaccinating half the number of people with two doses. In the long term, a second dose should ensure long-lived immunity, and so we encourage everyone who has had their first vaccine to ensure they receive both doses."

Some other vaccines, such as for flu, Ebola and malaria, also provide&nbsp;greater protection and stronger immune responses after a longer interval between doses.

The World Health Organization still recommends the use of AstraZeneca’s COVID-19 vaccine despite some research showing it’s less effective against a variant first found in South Africa, which has paused its rollout. The WHO says the vaccine still protects against the most severe cases.

AstraZeneca-Oxford vaccine more effective with longer dose gap, study suggests

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