How many people need to be vaccinated to get back to normal?

Herd immunity percentage is not a ‘magic threshold’

Margaret Keenan
Margaret Keenan was the first patient in the UK to receive the Pfizer/BioNtech vaccine
(Image credit: Jacob King/Pool/Getty Images)

Clinical tests from the various Covid-19 vaccine candidates last year offered a first glimmer of hope of a return to normality - but only now can the real-world impact of the jabs be assessed.

As countries worldwide race to inoculate populations against the coronavirus, the rollouts are beginning to affect rates of infections and related deaths. Here is what we can learn from the latest data on the main Covid vaccines.

1. Oxford-AstraZeneca vaccine

The Oxford-AstraZeneca vaccine appears to cut Covid infections by two-thirds according to the first “real-world data” on the impact of the jab, The Telegraph reports.

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The newly published figures - which will influence Boris Johnson’s lockdown exit roadmap - suggest that “just one dose of either the Oxford or Pfizer vaccines has such an effect on all age groups”, the paper says. And latest data also show that “Covid cases are falling most rapidly among the oldest, with care home outbreaks almost halving in a week”.

Meanwhile, a study by Public Health Scotland has found that by the fourth week after receiving the initial dose, the Oxford vaccine reduces the risk of hospitalisation with Covid by a “whopping” 94%, reports the Daily Mirror. The statistics were gathered between 8 December and 15 February, when 1.14 million vaccines were administered in Scotland, and give “great reasons to be optimistic for the future”, said lead researcher Professor Aziz Sheikh, director of the University of Edinburgh’s Usher Institute.

In an article published in The Spectator in January, John Roberts of the Covid-19 Actuary Response Group predicted that if the UK’s vaccine campaign went to plan, the country would see a 15% reduction in Covid cases by mid-March. Hospital admission would fall by 60%, while Covid-related deaths would drop by 88%, Roberts wrote.

Will the Oxford Covid vaccine be the true game-changer?

2. Pfizer-BioNTech vaccine

Although Israel is still in lockdown, a significant drop in coronavirus cases in the Middle Eastern country is being attributed largely to the speedy rollout of vaccines across the nation. The BBC reports that “the fall appears to be most pronounced in older people and areas furthest ahead in their immunisation efforts”.

Figures released at the start of February by the Israeli Ministry of Health show that just 0.07% (531) of almost 750,000 people aged over 60 who had been fully vaccinated had tested positive for Covid after getting the jab. And only 38 of those who were infected were hospitalised.

The Pfizer-BioNTech jab accounts for the majority of the vaccinations administered in Israel to date. According to Pfizer, research has found that the efficacy of the vaccine is “consistent across age” groups, providing 94% protection in patients over 64 - just 1% lower than the overall efficacy rate among all test subjects.

Latest figures from Public Health Scotland also indicate that the jab is beginning to have an impact in the UK. The same study that revealed encouraging results for the Oxford jab also found that the Pfizer vaccine caused a 85% reduction in hospitalisations within four weeks of the first dose being administered.

How does the Pfizer coronavirus vaccine work?

3. Moderna vaccine

Moderna’s long-awaited coronavirus vaccine candidate was found to be 94.5% effective in early clinical results published in November.

The jab is being widely used in the US, where a study of 62,138 patients between 1 December and 8 February found that the vaccine was 53.6% effective within the first seven days of the first dose being administered, rising to 88.7% after six weeks.

Among the vaccinated patients who did test positive for Covid after receiving the jab, the 14-day hospitalisation rate was 3.7%, compared with 9.2% among those who had not been inoculated.

Moderna has had effective Covid-19 vaccine since January

4. Janssen vaccine

The single-shot Covid vaccine developed by healthcare giant Johnson & Johnson is 85% effective at preventing the most serious coronavirus symptoms after a single dose, according to trials data published in late January.

The company said that the trials - conducted in several countries - also showed that the vaccine was 66% effective at preventing moderate to severe illness.

South Africa may provide the first real-world data on the impact of the Janssen vaccine, after the country began rolling out the jab its health care workers last week. Johnson & Johnson is awaiting Conditional Marketing Authorisation in the EU and has also applied for Emergency Use Authorisation in the US.

The UK has already ordered 30 million doses of the vaccine, which is pending approval by the Medicines and Healthcare products Regulatory Agency.

Janssen’s single-shot Covid-19 vaccine 85% effective

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