Even vaccinating 100 percent of the population may not be enough to eradicate COVID-19 once ‘super-covid’ variants become dominant in the US, a new study suggests.
Because the more infectious variant means each new case leads to a greater number of cases, vaccines – even the most effective ones – may not be able to outpace the rate of transmission.
Analysis from the University of East Anglia (UEA) found that the efficacy of the currently available vaccines, combined with the emergence of new more infectious strains of the virus, meant the reproduction rate will always stay above the dreaded level of one, meaning that for every one person infected with COVID-19, another one will catch the virus.
If the coronavirus‘s transmission rate could be slowed to an R number of one, the pandemic would be considered ‘stable.’ If it falls below one, infectious disease experts would consider the outbreak to be waning, slowing to a crawl that would effectively end the threat.
Currently, the US has an average R number of about 1.1. But arrival of the more infectious UK ‘super-covid’ variant – or, potentially, the South African and Brazilian variants not yet found in the US – threatens to drive that number up by about 70 percent, and potentially more. The Centers for Disease Control and Prevention (CDC) predicted last week that the UK variant could be dominant in the US by March.
US health officials like Dr Anthony Fauci have estimated that between 75 and 90 percent of Americans need to get vaccinated against COVID-19 in order for the US to reach herd immunity, at which point life could begin to return to normal.
But the more rapidly the virus is spreading, the more people need to be vaccinated for herd immunity to be reached.
The East Anglia study suggests that even the shot with the best efficacy rating – Pfizer’s, at 95 percent – would need to be given to be given to more than 80 percent of the population to bring the R number of the UK variant below one.
Even vaccinating 100 percent of the population with the more effective Pfizer and Moderna jabs would not drive the R number to zero, the researchers suggest. Less effective shots like Oxford University’s could not drive the R number below one even if 100 percent of the population received it.
While the two vaccines authorized in the US – Pfizer’s and Moderna’s – are each more than 94 percent effective, the rollout is moving at a glacial pace in the US, which has vaccinated just 5.2 percent of its population. If the US continues at its current rate of vaccination and the new variant takes hold, the new study suggests herd immunity through vaccination – rather than more illnesses – may disappear from reach.
On his very first day in office, President Biden signed 17 executive orders, including a mask mandate for all federal territories and properties and promised to get 100 million Americans vaccinated against COVID-19 in his first 100 days in office, but it’s a steep challenge.
Biden’s plans include opening 100 vaccination centers in stadiums and convention centers, funding states’ own mass vaccination sites and using the Defense Production Act to ramp up manufacturing of vaccine ingredients and supplies.
It could take weeks for the results of these new plans to show themselves, and the new study suggests time is more of the essence than ever with the already dire race between vaccination and the spread of coronavirus is heating up more still.
Even vaccinating 100 percent of the population with Pfizer’s 95% effective shot (green) would leave the transmission rate of the ‘super-covid’ variant from the UK above zero, while less effective shots like Oxford’s (red and blue) would fail to drive the R number below 1, at which point the pandemic would be considered ‘stable’
The US two vaccines authorized in the US are highly effective with Pfizer’s vaccine preventing 95 percent of infections and Moderna’s preventing 94 percent of COVID-19 cases.
But public health experts are fond of saying: Vaccines don’t save lives, vaccinations do.
US companies Moderna and Pfizer – with its German partner BioNTech raced ahead of much of the world to make high quality vaccines.
However, the US has fallen down on the vaccination front.
Only 17.2 million shots have been administered in the US – about 5.2 per every 100 people in the country – according to tracking from Bloomberg.
That comes out to an average of 912,497 doses injected per day over the past week.
If the US keeps up that rate, it will take nearly a year to get the entire population vaccinated – or about nine months to reach Dr Fauci’s lower herd immunity estimate of 75 percent.
Even at this rate, another 100,000 people are expected to die of COVID-19 in the next month, according to CDC projections.
It also suspects that the UK’s B117 variant could become dominant in the US by March, setting off yet another wave of infections, hospitalizations and deaths, akin to Britain’s, which has sent the nation into crisis mode.
In order to combat both the increased transmission rate, a vaccine needs to be highly effective and given efficiently to a large majority of a population.
The new University of East Anglia research, from Dr Paul Hunter and Dr Alastair Grant looked at the impact of coronavirus spread following a vaccination drive and when all non-pharmaceutical interventions (NPIs), such as social distancing and mask wearing, have been lifted.
In the US, Moderna’s and Pfizer’s vaccines have been authorized and found effective at preventing COVID-19, the illness caused by the coronavirus.
And in the UK, the same two vaccines plus the less effective but far cheaper and easier to handle shot from Oxford University and AstraZeneca have been approved.
However, it remains unknown whether the shots can prevent infection itself or transmission.
‘We don’t know if any of the vaccines provide sterilizing immunity,’ Professor Hunter told MailOnline.
‘As far as we can tell, if you are to stop somebody spreading the infection, you need sterilizing immunity.’
And the UAE study found that the high efficacy of vaccines and the herd immunity threshold that goes with their effectiveness may only hold true for older variants of coronavirus.
The more infectious B117 variant that emerged in the UK may require an overhaul of the herd immunity equation.
Moderna’s vaccine was not included in the analysis, but it is similarly effective to the Pfizer shot, and the researcher’s referred to the two interchangeably.
Oxford’s vaccine is not yet authorized in the US, but likely will be in the coming months.
The two vaccines being used in the US are more effective, bu the rollout may not be moving fast enough to keep up with the more transmissible virus
Data shows vaccinating 69 percent of the population with Pfizer’s jab, which is 95 percent effective, would be enough for herd immunity against the old strain.
The study also noted that 93 percent of the UK population would need to be vaccinated with Oxford’s jab to reach herd immunity.
The models are based on the UK, but the principle holds true for the US.
The UK is vaccinating people more quickly than the US, but one of its three shots is less effective than the two being used in the US. And in the UK, the R number is between 1.2 and 1.3, compared to 1.1 in the US.
But when accounting for the new variant, which the academics assume is 56 percent more infectious (although other research has suggested it is 70 percent more or even twice as contagious), the equation changes dramatically.
‘Vaccinating the entire population with the Oxford vaccine would only reduce the R value to 1.325 while the Pfizer vaccine would require 82 percent of the population to be vaccinated to control the spread of the new variant,’ the researchers write in their study, which has not yet been peer-reviewed but is available online a preprint.
The researchers included the Kent strain, which has been identified in at least 17 US states an now accounts for at least 61 percent of all UK infections, in their analysis, but did not have enough data to look at the impact of the South Africa variant.
The UK variant does not seem to be an escape mutant as it is lacking the E484K gene,’ Dr Hunter says.
The E484K gene mutation is believed to make the virus adept at avoiding antibodies which have been made by the human immune system following prior infection.
As a result, it is to blame for numerous reinfection events and scientists are growing increasingly concerned it may be able to evade current vaccines.
‘The problem with the English strain is it spreading more quickly,’ Professor Hunter adds.
‘The South Africa strain is a different matter and has both the increased infection mutant and a degree of escape mutant.
‘This does not necessarily mean the vaccine is useless but is probably slightly less effective.’
Dr Jonathan Stoye from the Francis Crick Institute, who was not involved in the study, comments on the paper: ”It reaches the provocative conclusion that administration of the Adenovirus based vaccine from Oxford/AstraZeneca alone, despite a major reduction in the seriousness of COVID-19 disease, is unlikely to generate the herd immunity needed for complete control of virus spread.
‘Based on the data currently available, this study appears strong and the conclusion unarguable.
‘It points to a continuing role for non-pharmaceutical interventions such as the wearing of face masks and hand washing as well as suggesting a possible utility for booster vaccinations with RNA based delivery systems.’
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