Sunday, November 07, 2021

Effectiveness of vaccines against infection less than 50% on average

But good at preventing death

The protection that fully vaccinated Americans have against COVID-19 infection severely drops over time, a new study suggests.

A team led by the Public Health Institute in Oakland, California, found that the overall effectiveness of the three Covid vaccines available in the U.S fell from 87 percent in March to 48 percent by September.

Johnson & Johnson vaccine recipients are especially at risk with just 13 percent efficacy against contracting the virus.

However researchers found that the shots are still highly protective against death from Covid.

Researchers, who published their findings on Thursday in the journal Science, gathered data from the Veterans Health Administration from February to October 2021.

In total, nearly 800,000 veterans' data was included in the massive study.

The team analyzed vaccine records among people who tested positive for the virus, and determined, on average, how effective each individual jab was at preventing infection.

In February, when the vaccines were still relatively new, they all had an effectiveness of more than 85 percent at preventing infection.

J&J's vaccine saw its protection wane the most, dropping from 86 percent in March to below 50 percent by September, and down to only 13 percent last month.

The Pfizer-BioNTech jab - which is far and away the most commonly used in the U.S. - saw its effectiveness drop from 87 percent in March to 43 percent in September.

September was the first month during which the effectiveness of Pfizer's vaccine dropped below 50 percent.

Moderna's shot held up the best, and is the only one of the three to still be more than 50 percent effective.

The shot's effectiveness has still fallen greatly, though, from 89 percent in March to 58 percent in September.

Overall, the three vaccines' effectiveness was 87.9 percent in March, and dropped to 48.1 percent in September.

'By July 2021, the U.S. experienced a surge in cases of COVID-19, dominated by the [Delta] variant,' the researchers wrote.

'Initial reports, including follow-up of the Pfizer-BioNTech and Moderna trials, suggested sustained vaccine protection, but three reports of the U.S. Centers for Disease Control in August 2021 demonstrated protection against infection had declined in mid-summer as the Delta variant rose to dominance.

'Protection against hospitalization and death remained high. Breakthrough infections, illness, hospitalizations, and deaths have since continued to emerge in vaccine recipients.'

This waning immunity is the source behind the federal goverment's push for Covid vaccine boosters for all Americans.

Last month, additional shots of the vaccines became available to Americans over the age of 65 with severe comorbidities or who have a job that puts them at risk of virus exposure.

The goal behind the booster rollout is to shore up immunity from the virus and prevent breakthrough infections.

Many opposed the booster rollout, though, because the shots are still effective at preventing death from the virus.

The new study found that an unvaccinated person under the age of 65 is 2.6 percent likely to die from the virus, while that risk drops to 1.6 percent with vaccination.

Those who received the Pfizer shot had their risk of death slashed by 84 percent, the most effective of the three.

The Moderna shot reduced risk of death by 82 percent and the J&J by 73 percent. The numbers are even more drastic for people over the age of 65.

For the elderly, risk of death from Covid if unvaccinated is over 20 percent. Fully vaccinated people over the age of 65 only died from the virus nine percent of times, the researchers found.

The Moderna shot was most effective at preventing death among people 65 and older, reducing risk by 75 percent.

The Pfizer shot reduced the elderly's risk of death by 70 percent and the J&J did by 52 percent.

The death rate among fully vaccinated people over 65 is still high, though, underscoring why health officials are targeting boosters at that group in particular.

The Centers for Disease Control and Prevention reports that more than 21 million Americans have received a COVID-19 booster shot, with a majority opting for the Pfizer shot.


Pfizer's at-home Covid pill 'cuts risk of dying by nearly 90%'

First Merck and now Pfizer

Pfizer today claimed its at-home Covid pill cuts the risk of severe illness by nearly 90 per cent, potentially providing the UK with another weapon in its arsenal to combat the pandemic.

Its twice-a-day antiviral was shown in clinical trials to slash the risk of hospitalisation or deaths by 87 per cent in vulnerable and elderly patients.

The pharmaceutical giant stopped its study of the drug — known as Paxlovid — early due to the 'overwhelming efficacy'.

The findings appear to surpass those seen with Merck's rival pill molnupiravir, which data showed halved the risk of death or hospitalisation.

Paxlovid can be taken at home and is a combination of an experimental drug with an older antiviral called ritonavir, already used to treat HIV/AIDS.

Pfizer described its findings as a 'game-changer' and now plans to apply for approval from American medical regulators in the coming days. The firm will likely also seek approval in the UK, where the Government has already purchased 250,000 courses.

It comes after Britain yesterday became the first country in the world to give Merck's antiviral the green light, paving the way for it to be rolled out on the NHS within the next few weeks.

Announcing the findings, Pfizer's chief executive Albert Bourla said: 'Today's news is a real game-changer in the global efforts to halt the devastation of this pandemic.

'These data suggest that our oral antiviral candidate, if approved or authorized by regulatory authorities, has the potential to save patients' lives, reduce the severity of Covid infections, and eliminate up to nine out of ten hospitalizations.'

Pfizer's drug, part of a class known as protease inhibitors, is designed to block an enzyme the coronavirus needs in order to multiply.

It is given with ritonavir to make sure it stays active in the body for a longer period of time.

Merck's molnupiravir has a different mechanism of action designed to introduce errors into the genetic code of the virus.

It's hoped that the drug will be bulletproof against new variants because it targets an enzyme produce in the body.

Pfizer's drug is part of a class known as protease inhibitors. It is designed to block an enzyme the coronavirus needs in order to multiply. Like protease inhibitors used to treat HIV, it is given in combination with other antivirals.

How effective is it?

A recent trial of the pill in more than 1,200 found that it cut hospitalisation and death rates by 87 per cent in people at high risk of a severe illness from Covid.

It should be given as soon as possible after catching Covid, ideally within three to five days.

Vaccines, which are being made slightly weaker by new strains of the virus, work by targeting the spike protein and were designed to tackle the original virus.

Because a lot of evolution happens on the spike protein, the immune systems of vaccinated people sometimes find it more difficult to recognise new variants.

Pfizer said Paxlovid works best when given to a patient within three days of testing positive.

The study of the pill included around 1,200 patients who were mostly vaccinated and had recently tested positive.

It looked at patients with at least one risk factor for developing severe disease, such as obesity or older age.

It found that 0.8 per cent of those given Pfizer's drug were hospitalised and none had died by 28 days after treatment.

For comparison, the hospitalisation rate stood at 7 per cent for the patients given a placebo. There were also seven deaths in the placebo group.

Annaliesa Anderson, head of the Pfizer programme, said: 'We saw that we did have high efficacy, even if it was five days after a patient has been treated.

'People might wait a couple of days before getting a test... and this means we have time to treat people and really provide a benefit from a public health perspective.'

The company did not detail side effects of the treatment, but said adverse events happened in about a fifth of both treatment and placebo patients.

Pfizer is also studying whether its pill could be used by people without risk factors for serious Covid as well as to prevent coronavirus infection in people exposed to the virus.

Health and Social Care Secretary Sajid Javid said: 'Incredible results from Pfizer showing their antiviral medicine cuts the risk of hospitalisation or death from COVID-19 by almost 90 per cent.

'We have procured 250,000 doses of this promising treatment on behalf of the whole UK and our independent medicines regulator, the MHRA, will now assess its safety, quality and effectiveness.

'If approved, this could be another significant weapon in our armoury to fight the virus alongside our vaccines and other treatments, including molnupiravir, which the UK was the first country in the world to approve this week.'




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