Public Health England and AstraZeneca representatives did not respond to requests for comment.
Both Pfizer and AstraZeneca vaccines introduce a protein called spike into the body that, while not infectious in itself, can teach immune cells to recognize and fight off the actual coronavirus.
Answers to your vaccine questions
With a coronavirus vaccine spreading out of the US, here are answers to some questions you may be wondering about:
- If I live in the US, when can I get the vaccine? While the exact order of vaccine recipients may vary from state to state, most doctors and residents of long-term care facilities will come first. If you want to understand how this decision is made, this article will help.
- When can I get back to normal life after the vaccination? Life will only get back to normal once society as a whole receives adequate protection against the coronavirus. Once countries have approved a vaccine, they can only vaccinate a few percent of their citizens in the first few months. The unvaccinated majority remain susceptible to infection. A growing number of coronavirus vaccines show robust protection against disease. However, it is also possible that people spread the virus without knowing they are infected because they have mild symptoms or no symptoms at all. Scientists don’t yet know whether the vaccines will also block the transmission of the coronavirus. Even vaccinated people have to wear masks for the time being, avoid the crowds indoors and so on. Once enough people are vaccinated, it becomes very difficult for the coronavirus to find people at risk to become infected. Depending on how quickly we as a society achieve this goal, life could approach a normal state in autumn 2021.
- Do I still have to wear a mask after the vaccination? Yeah, but not forever. Here’s why. The coronavirus vaccines are injected deep into the muscles and stimulate the immune system to produce antibodies. This seems to be sufficient protection to prevent the vaccinated person from getting sick. What is not clear, however, is whether it is possible for the virus to bloom in the nose – and sneeze or exhale to infect others – even if antibodies have been mobilized elsewhere in the body to prevent that vaccinated person gets sick. The vaccine clinical trials were designed to determine if people who were vaccinated are protected from disease – not to find out if they can still spread the coronavirus. Based on studies of flu vaccines and even patients infected with Covid-19, researchers have reason to hope that vaccinated people won’t spread the virus, but more research is needed. In the meantime, everyone – including those who have been vaccinated – must imagine themselves as possible silent shakers and continue to wear a mask. Read more here.
- Will it hurt What are the side effects? The vaccine against Pfizer and BioNTech, like other typical vaccines, is delivered as a shot in the arm. The injection in your arm feels no different than any other vaccine, but the rate of short-lived side effects seems to be higher than with the flu shot. Tens of thousands of people have already received the vaccines, and none of them have reported serious health problems. The side effects, which can be similar to symptoms of Covid-19, last about a day and are more likely to occur after the second dose. Early reports from vaccine trials suggest that some people may need to take a day off because they feel lousy after receiving the second dose. In the Pfizer study, around half developed fatigue. Other side effects occurred in at least 25 to 33 percent of patients, sometimes more, including headache, chills, and muscle pain. While these experiences are not pleasant, they are a good sign that your own immune system is having a strong response to the vaccine that provides lasting immunity.
- Will mRNA vaccines change my genes? No. Moderna and Pfizer vaccines use a genetic molecule to boost the immune system. This molecule, known as mRNA, is eventually destroyed by the body. The mRNA is packaged in an oily bubble that can fuse with a cell, allowing the molecule to slide inside. The cell uses the mRNA to make proteins from the coronavirus that can stimulate the immune system. At any given point in time, each of our cells can contain hundreds of thousands of mRNA molecules that they produce to make their own proteins. As soon as these proteins are made, our cells use special enzymes to break down the mRNA. The mRNA molecules that our cells make can only survive a few minutes. The mRNA in vaccines is engineered to withstand the cell’s enzymes a little longer, so the cells can make extra viral proteins and trigger a stronger immune response. However, the mRNA can last a few days at most before it is destroyed.
However, the vaccines convey their immunological teachings in different ways and do not contain equivalent ingredients. While Pfizer’s vaccine relies on a molecule called messenger RNA, or mRNA, wrapped in greasy bubbles, AstraZeneca’s images are based on a viral envelope that provides DNA, a cousin of mRNA.
Both vaccines should be given in a two-shot regime with an interval of three or four weeks. While the first shots of any vaccine are considered somewhat effective in preventing Covid-19, it is the second dose – which is meant to be a kind of molecular screening session for the immune system – that triggers the protection process.
While it is possible that swapping one vaccine for another could still train the body to recognize the coronavirus, it is still a scientific gamble. With different ingredients in each vaccine, it is possible that people will benefit less from a second shot. Mixing and matching could also make it more difficult to collect clear vaccine safety data.
With no evidence to support this, the hybrid vaccination approach seems “premature,” said Saad Omer, a vaccines expert at Yale University. Still, it’s not without precedent: health officials like the CDC have previously said that if it is impossible to give doses of a vaccine from the same manufacturer, “providers should give the available vaccine” to complete an injection schedule.
In a controversial move, the UK government also decided earlier this week to pre-load the vaccine rollout and give people as many first doses as possible – a move that could delay the second shots by up to 12 weeks.
Rapid deployment could provide partial protection against the virus to more people in the short term. Some experts, including Dr. Moore, however, fear that this too could be unwise and endanger vulnerable populations.