National vaccine program key driver in reduced COVID cases: Study

Matt Woodley

10/05/2021 5:23:12 PM

Real-world data has added further weight to the potential public health benefits of mass-vaccination against the coronavirus.

Close up of the Pfizer COVID vaccine.
Two doses of the Pfizer vaccine have reportedly provided 91.5% protection against asymptomatic COVID infection. (Image: AAP)

Newly-released data from Israel – which has the highest COVID vaccination coverage in the world – has revealed the potential impact effective vaccination campaigns can have against the coronavirus.
The analysis, published in The Lancet and based on de-identified national data, found it has been the key driver of declining COVID-19 infections in the country, along with the vast majority of serious health impacts associated with the disease.

The study’s lead author, Dr Sharon Alroy-Preis, said it provides a ‘unique real-world opportunity’ to determine the effectiveness of the vaccine and to observe wider effects of a national vaccination program on public health.

‘Until this point, no country in the world had described the national public health impact of a nationwide COVID-19 vaccination campaign,’ she said.
‘These insights are hugely important because, while there are still some considerable challenges to overcome, they offer real hope that COVID-19 vaccination will eventually enable us to control the pandemic.’
According to the results, two doses of the Pfizer vaccine have so far provided more than 95% protection against infection, hospitalisation, severe illness, and death, and also substantially reduced asymptomatic infection.
The vaccination program began on 20 December last year amidst a surge in cases that peaked exactly one month later on 20 January when daily infections reached 10,213.
However, by 7 March a nationwide lockdown that began in early January had been lifted, and less than one month later nearly three quarters of people over 16 (72%), and 90% of those over 65 years, had received two doses of the Pfizer vaccine.
Infections among those over 65 years continued to rise until mid-January, peaking at around 55 cases per 100,000.
However, infections started to decline as people began receiving their second vaccine doses, with daily cases of around 30 per 100,000 by the first phase of reopening on 7 February.
Daily infections also continued to decline markedly as more people received the vaccine, with steeper and swifter declines observed for people over 65 years of age – reflecting higher and earlier vaccination rates among older people.

By 24 April, Israel registered zero COVID deaths for the first time in 10 months, and it is currently recording less than 58 confirmed cases per day.

However, while the authors said the findings are encouraging, they also stressed there are still a number of ongoing challenges related to controlling the pandemic. For example, the duration of immunity to COVID-19 – both from infection and immunisation – remains unknown, and it is possible that new, vaccine-resistant variants could emerge in the future.
During the analysis period, the B.1.1.7 variant accounted for 94.5% of specimens confirmed via PCR testing, whereas rates of B.1.351 – which has been found to reduce effectiveness in other vaccine candidates – were too low to produce vaccine efficacy estimates.
In addition, achieving herd immunity will require a continued increase of vaccination coverage worldwide, and the researchers cautioned differences between countries in how vaccines are rolled out and how the pandemic continues to evolve would also likely impact further results.
Along with showing the potential impact a mass vaccination program can have on limiting the spread of COVID, the research was also able to demonstrate the importance of people being fully vaccinated.
All people over the age of 16 years received 95.3% protection against infection and 96.7% protection against death seven days after the second dose, while protection against asymptomatic infection was recorded at 91.5%.
However, effectiveness was considerably lower after receiving the first dose, with it providing only 57.7% protection against infection, 75.7% against hospitalisation, and 77% against death.

The authors also pointed out that little is known about the duration of protection of one dose and how this compares to two doses, and caution that one dose may provide a shorter window of protection, particularly in an environment where new variants continue to emerge.

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