The AstraZeneca vaccine is shown to cut transmission of the virus.
Developed by Oxford University and AstraZeneca, the vaccine not only protects people from serious illness and death, but also significantly slows down the transmission of the virus, according to a new study – a finding that underscores the importance of mass vaccination as a way out of the pandemic.
Oxford University researchers measured the effects on transmission by swabbing participants each week to look for any signs of the virus. In the absence of a virus, it cannot be spread even if someone is infected. And they found a 67 percent reduction in positive swabs among those vaccinated.
The results, detailed by Oxford and AstraZeneca researchers in a non-peer-reviewed manuscript, found that the vaccine could reduce transmission by nearly two-thirds.
Matt Hancock, the UK Health Secretary, hailed the results on Wednesday as “absolutely outstanding”.
“We now know that the Oxford vaccine will also reduce transmission and help us all get out of this pandemic,” Hancock said in an interview with the BBC on Wednesday morning.
The results, he said, “should give everyone confidence that this shock will not only serve to protect you, but also to keep you from passing the virus on to others.”
Some scientists studying the limited information published warned that further analysis of the data would be needed before such broad conclusions could be drawn.
“While this would be extremely welcome news, we need more data before this can be confirmed, so it is important that we all continue to follow social distancing guidelines after vaccination,” said Dr. Doug Brown, executive director of the British Immunology Society.
The Oxford and AstraZeneca researchers also found that a single dose of the vaccine was 76 percent effective against Covid-19. The data was measured three months after the first shot, with no initial three week period required for the protection to take effect.
The encouraging results support the UK and other countries strategy of prioritizing the provision of as many first doses of vaccine as possible and ignore concerns that people will receive their second doses later than originally planned.
The latest data does not affect the debate over whether to further reduce doses of the two US-approved vaccines Pfizer-BioNTech and Moderna, as the data on AstraZeneca’s candidates cannot be transferred to other vaccines.
Some scientists have urged the United States to follow the example of the UK and other countries who have chosen to postpone the second dose of vaccine for up to 12 weeks. But U.S. federal officials refused, saying such a move would not be supported by clinical trial data for the two vaccines currently available nationwide. Tuesday’s results could add to pressure on US health officials to postpone AstraZeneca’s second dose of vaccine, even though it has not yet been approved by the country.
The vaccine appeared to be more effective when the interval between the two shots was longer than the four-week interval originally intended, the Oxford and AstraZeneca researchers found. Among clinical trial participants who received two standard strength doses at least three months apart, the vaccine was 82 percent effective, compared with 55 percent when the doses were given less than six weeks apart.
Answers to your vaccine questions
Am I eligible for the Covid vaccine in my state?
Currently more than 150 million people – almost half of the population – can be vaccinated. But each state makes the final decision on who goes first. The country’s 21 million healthcare workers and three million long-term care residents were the first to qualify. In mid-January, federal officials asked all states to open eligibility to anyone over 65 and adults of any age with medical conditions that are at high risk of becoming seriously ill or dying of Covid-19. Adults in the general population are at the end of the line. If federal and state health authorities can remove bottlenecks in the distribution of vaccines, everyone over the age of 16 is eligible as early as spring or early summer. The vaccine has not been approved in children, although studies are ongoing. It can take months before a vaccine is available to anyone under the age of 16. For the latest information on vaccination guidelines in your area, see your state health website
Is the Vaccine Free?
You shouldn’t have to pay anything out of pocket to get the vaccine, despite being asked for insurance information. If you don’t have insurance, you should still get the vaccine for free. Congress passed law this spring banning insurers from applying cost-sharing such as a co-payment or deductible. It consisted of additional safeguards prohibiting pharmacies, doctors, and hospitals from charging patients, including uninsured patients. Even so, health experts fear that patients will end up in loopholes that make them prone to surprise bills. This may be the case for people who are charged a doctor’s visit fee with their vaccine, or for Americans who have certain types of health insurance that are not covered by the new regulations. When you get your vaccine from a doctor’s office or emergency clinic, talk to them about possible hidden costs. To make sure you don’t get a surprise invoice, it is best to get your vaccine from a Department of Health vaccination center or local pharmacy as soon as the shots become more widely available.
Can I choose which vaccine to get?How long does the vaccine last? Do I need another next year?
That is to be determined. It is possible that Covid-19 vaccinations will become an annual event just like the flu vaccination. Or the vaccine may last longer than a year. We’ll have to wait and see how durable the protection from the vaccines is. To determine this, researchers will track down vaccinated people to look for “breakthrough cases” – those people who get Covid-19 despite being vaccinated. This is a sign of a weakening of protection and gives researchers an indication of how long the vaccine will last. They will also monitor the levels of antibodies and T cells in the blood of people who have been vaccinated to see if and when a booster shot might be needed. It is conceivable that people might need boosters every few months, once a year, or just every few years. It’s just a matter of waiting for the data.
Does my employer need vaccinations?Where can I find out more?
A vaccination strategy that cuts doses by three months “might be the optimum for pandemic vaccine rollout when supplies are limited in the short term,” the researchers wrote.
The newly published study builds on data published late last year. The vaccine was found to be 62 percent effective at two standard strength doses. In these initial findings, the vaccine effectiveness was 90 percent much higher when the first dose of the vaccine was given at half strength.
The researchers from Oxford and AstraZeneca initially attributed the different levels of effectiveness to the lower strength of the initial dose. Gradually, however, they came to a different conclusion: the time between doses was the more likely explanation.
In the United States, the Food and Drug Administration is waiting for data from a clinical trial that involved around 30,000 participants, mostly Americans. The results of this study are expected later this month.
The study is expected to provide AstraZeneca with enough safety data to enable it to obtain approval to make the emergency vaccine available by early March.
The United States has agreed to purchase 300 million doses of the vaccine from AstraZeneca, but neither the company nor the federal government has indicated when and in what quantities those doses will be available after the vaccine is approved.