Why Did The Uk Decide To Extend The Gap Between Doses
UK cases of Covid-19 were surging last December, along with hospitalisations and deaths, and there was a risk that the NHS could be overwhelmed. In light of this, health authorities decided that it would be better to give the protection of a first dose to as many people as possible, as fast as possible. That meant delaying second doses, on the grounds that they would add only limited extra protection to people who already had significant immunity from their first dose.
This policy was recommended by the independent experts on the Joint Committee on Vaccination and Immunisation an independent expert group that advises the UK health departments and the UKs Chief Medical Officers agreed.
Ideally, researchers would run a set of clinical trials to compare different dosing schedules and then authorities would make policy based on plenty of solid data. But in the face of a public health emergency, waiting would have cost lives. The decision was based on limited data from the vaccine trials in 2020, coupled with expert judgement about how vaccines generally work.
Evidence that has appeared since then is, so far, vindicating that decision.
Coronavirus Vaccine 3rd Dose
People with a weakened immune system are being offered a 3rd dose of a coronavirus vaccine. This is also known as a 3rd primary dose.
If you had a weakened immune system when you had your first 2 doses, the vaccine may not have given you as much protection as it can for people who do not have a weakened immune system.
A 3rd dose may help give you better protection.
The 3rd vaccine dose for people with a weakened immune system is different to a COVID-19 vaccine booster dose.
Is It Ok To Get The Covid
While there have been reports of severe allergic-type reactions in a very small number of patients, the CDC says that people with allergies to certain foods, drugs, insects, latex and other common allergens can still get the COVID-19 vaccine.
If you have had a severe allergic reaction to injectables or other vaccines, be sure to discuss the COVID-19 vaccination with your doctor, who can evaluate you and assess your risk. The vaccine provider should observe you for 30 minutes rather than the routine 15 minutes after vaccination, and if you have an allergic reaction to the first shot, you may not receive the second.
The CDC says that at this time, anyone who has a severe allergy to any of the vaccine ingredients should not get that vaccine.
How Do We Know a COVID-19 Vaccine Will Be Safe and Effective?
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These Measurements May Not Be Suitable For All Virus Variants
The London Medical Laboratory COVID-19 antibody test is a quantitative measurement of IgG antibodies against the spike receptor binding domain of COVID-19. The RBD is the part of the virus that allows it to lock on to body receptors to gain entry into body cells. Rohde advises that this specific binding domain may not be the best measurement for future COVID-19 variants, such as when we learn more about Omicron.
How Does Immunity From A Vaccine Compare To Immunity From Infection
Vaccine-induced immunity and natural immunity both provide protection against getting the infection in the future. Which one provides better immunity can depend on the type of infection it is.
We are still learning about COVID-19 and immunity, but a recent study showed that vaccine-induced immunity was better than natural immunity in protecting against COVID-19. Getting the vaccine also allowed the immune system to recognize other coronavirus strains, which could provide protection against new variants that develop.
An important advantage of any vaccine-induced immunity is that you can get immunity without actually getting sick. For COVID-19, this is especially important because even if you recover from it, many people continue to have debilitating symptoms for months.
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A Mild Reaction To The Vaccine Is Just Your Immune System Working
Dr. Marks says a lot of people wonder what it means if they experience side effects, such as a fever or arm rash, and if that should prevent them from getting their second dose. These mild side effects are actually just your immune system responding. They are often more pronounced after the second dose. It means you have a vigorous immune system when you get those reactions, says Dr. Marks. If people didnt feel well at the first dose, they should be prepared for that possibility again and make sure they take some extra time if they need it. If you had an allergic reaction or a very severe reaction from the first dose, you should talk to your doctor, but otherwise people should get the second dose.
At the same time, people should not worry if they feel no effects after getting the vaccine. We know from the studies, some people also have no reaction to the vaccine, says Dr. Marks. So if you do not experience these mild reactions this is not a cause for concern either.
Preclinical Trials Would Have Shown That They Didn’t Think There Was Enough Immunity After One Shot So They’ve Gone For Both Deborah Dunn
However, this early protection comes with some important caveats. First, the protection doesn’t kick in until at least day 12 until then, there was no difference between the two groups. Secondly, one dose is still significantly less protective than two. The latter is 95% effective at preventing the disease after a week.
But there is also another figure that has been circulating on the internet, and anecdotally, being fed to patients by certain doctors the suggestion that the first dose is around 90% effective. And this is where it gets a little more complicated.
The second estimate comes from the UK’s Vaccine Committee, the JCVI, who decided to calculate the efficacy of the vaccine differently. Instead of using all the data on the number of infections, including from days when the first dose hadn’t yet started to work, they only looked at days 15-21. Using this method, the efficacy of the vaccine jumps up to 89%, because it’s not being diluted by the relatively high number of infections before the vaccine begins to have an effect. Taking things even further and only looking at the first seven days after the second dose because the second dose might not have kicked in yet by then it’s 92%.
However, these calculations are controversial.
A vaccine developed to fight Ebola is the only one that uses the same technology as the Russian and Oxford-AstraZeneca Covid-19 jabs
Can you skip the second vaccine dose?
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Booster Provided Best Protection
However, only the participants receiving the booster vaccination demonstrated robust Omicron pseudovirus neutralization, while the other groups showed substantial decreases in neutralization capability.
When researchers compared blood samples from the group recently receiving the primary series of the COVID-19 vaccines to those receiving a booster vaccine within the last 3 months, they found that those receiving boosters had a greater scope and cross-reactivity of neutralizing antibody response to the Omicron pseudovirus.
The researchers then tested the pseudoviruses ability to infect cells with and without the ACE2 receptors. ACE2 receptors are necessary for cell entry of SARS-CoV-2 in the body.
As expected, none of the pseudoviruses infected cells without ACE2 receptors. In cells with ACE2 receptors, the Omicron pseudovirus infected cells at a four times higher rate than the wild-type and twice the rate of Delta.
First What About Immunity Following Covid
The presence of antibodies against SARS-CoV-2 is used as an indicator of immunity, with higher levels indicating greater protection. Once antibody levels drop below a particular threshold, or vanish completely, the person is at risk of reinfection.
Initially, scientists observed peoples antibody levels rapidly decreased shortly after recovery from COVID-19.
However, more recently, weve seen positive signs of long-lasting immunity, with antibody-producing cells in the bone marrow identified seven to eight months following infection with COVID-19. In addition, scientists have observed evidence of memory T cells more than six months following infection.
A study of over 9,000recovered COVID-19 patients in the United States up to November 2020 showed a reinfection rate of only 0.7%. These findings closely align with a slightly more recent study suggesting reinfection after COVID-19 is very uncommon, at least in the short term.
While it seems likely theres some level of lasting protection following COVID-19 infection, if youve had COVID, getting vaccinated is still worthwhile.
Theres some evidence vaccination after recovery leads to a stronger level of immunity compared to natural immunity from infection, or immunity from vaccination alone. People with so-called hybrid immunity appear to exhibit a more diverse range of antibodies.
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S To Take After Vaccination
According to William Moss, MD, MPH, executive director of the International Vaccine Access Center at John Hopkins in Baltimore, it’s crucial that people continue wearing masks even after getting their shots.
Even after vaccination, a large percentage of the population may not be protected because the vaccine isn’t 100% effective against COVID-19.
If 95% efficacy holds up, 5% of people who get the vaccine will not be protected after receiving vaccination, Moss told Verywell. That sounds like a small percentage, but when youre vaccinating millions of people, thats a large number of people.
How Long After The First Dose Should You Have The Second Dose
The UK introduced its policy of leaving a 12-week gap between Covid-19 vaccine doses at the end of December 2020. This is at the top end of the range recommended by the makers of the Oxford-AstraZeneca vaccine but is much longer than recommended for the Pfizer-BioNTech vaccine .
Leaving the second dose too late is risky, because the effects of the first dose might start to weaken. But giving the second dose too soon is also risky, because your immune system needs time to fully react to the first dose so that it can then get maximum benefit from the second.
For the new Covid-19 vaccines, we dont yet know what the ideal gap is it takes time to test this. But the evidence is positive about longer delay.
For the Oxford-AstraZeneca vaccine, data from clinical trials suggests that a single dose gives good protection against illness for more than 12 weeks, and that the booster effect of the second dose is stronger when the gap between doses is longer.
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Being Fully Vaccinated Gives You Protection But For How Long
Analysis from the Zoe Covid Study app, which invites users to log Covid-19 vaccines to monitor their side-effects and effectiveness, suggested the Pfizer jab was 88% effective at preventing Covid-19 infection a month after the second dose, but after five to six months, protection decreased to 74%.
The AstraZeneca vaccine offered 77% protection against infection one month after the second dose, but after four to five months, protection decreased to 67%.
But again, this data comes from the original strain of Covid. We know vaccines are less effective against the Delta and Omicron variants, which is why having a booster dose is key.
First Covid Vaccine Dose: What Can You Do After Your First Shot
The U.S. hit a new high for the number of daily Covid-19 vaccinations Saturday: 4 million. The record was set as vaccinations have steadily risen over recent weeks, bringing the daily average to more than 3 million.
That means more people in the U.S. are receiving one dose of a Covid-19 vaccine every day. For the majority, who will get either the Pfizer-BioNTech or the Moderna vaccine, it’s just the first dose in three to four weeks, they’ll return for a second.
But is a person protected after just the first shot?
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If I Get A Coronavirus Vaccination Do I Still Have To Wear A Mask Physical Distance
The CDC continues to monitor the spread of COVID-19 and makes recommendations for wearing face masks, both for those who are fully vaccinated as well as those who are not fully vaccinated.
The CDC also recommends that masks and physical distancing are required when going to the doctors office, hospitals or long-term care facilities, including all Johns Hopkins hospitals, care centers and offices.
Johns Hopkins Medicines current mask safety guidelines have not changed, and we still require all individuals to wear masks inside all of our facilities.
What Are Covid Booster Side Effects
After getting vaccinated for COVID-19, you might experience some temporary symptoms similar to those you might notice when you get a flu shot, such as a sore, swollen arm where you got the shot. You might run a fever and experience body aches, headaches and tiredness for a day or two. Chills, swollen lymph nodes can also occur.
These symptoms do not mean you are sick. They signal that your immune system is responding to the shots and building up protection against the coronavirus.
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How Will A Vaccine Prevent Covid
The coronavirus that causes COVID-19 has spikes of protein on each viral particle. These spikes help the viruses attach to cells and cause disease. Some of the coronavirus vaccines are designed to help the body recognize these spike proteins and fight the coronavirus that has them.
An effective vaccine will protect someone who receives it by lowering the chance of getting COVID-19 if the person encounters the coronavirus. More important is whether the vaccine prevents serious illness, hospitalization and death. At this time, all three vaccines are highly efficacious at preventing serious illness, hospitalization and death from COVID-19. Widespread vaccination means the coronavirus will not infect as many people. This will limit spread through communities and will restrict the viruss opportunity to continue to mutate into new variants.
How Effective Is The First Shot Of The Pfizer Or Moderna Vaccine
Editors note: Since this article was initially published, the coronavirus has continued to mutate. This updated version reflects research as of July 2021 suggesting that a single dose of the Moderna or Pfizer COVID-19 vaccine is not enough to reliably ward off infection. The recommendation remains to receive the full course of two shots.
Maybe youve postponed your second COVID-19 vaccine appointment, whether because of scheduling hassles or general reluctance. But how safe are you after just a single dose?
As an immunologist, I hear this question frequently and the answer has changed as new genetic strains of the coronavirus become more common. , the delta variant had become the most dominant strain of SARS-CoV-2 circulating in the U.S.
The Moderna and Pfizer mRNA vaccines werent designed specifically to ward off the delta variant. While overall they still provide excellent protection after the full two doses, new research suggests a single dose provides less immunity against the coronavirus strains that are out there now than it did against the original strain.
Bottom line: Two shots are way better than one.
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How Are We Monitoring The Coronavirus Vaccines
Pfizer and Moderna have been monitoring immunity in people who were given their vaccines in the initial clinical trialsboth companies had reported strong overall efficacy at the six-month mark.
One thing researchers are monitoring in vaccine recipients is levels of antibodies, which are proteins produced by the bodys immune system when it detects harmful substances, and that are easily measured from blood samples. Antibodies are a really good marker for protection against infection, so we will be monitoring those levels for as long as we can measure them, says Akiko Iwasaki, PhD, a professor of immunobiology at Yale School of Medicine.
I tell my family, ‘It’s great that youre vaccinated… But even the vaccines dont have 100% guarantees, so… you want to keep weighing the risks,'” says Yale Medicine infectious diseases expert Jaimie Meyer, MD, MS
A report in The New England Journal of Medicine in April showed that 33 participants who had received the Moderna vaccine during the Phase I trial had a gradual decline in antibody protectionand, based on the slope, Iwasaki says, that is hopeful news. If antibodies are going down very quickly, you would expect that to last for a short time. The slow decline raises hopes that the mRNA vaccines will be protective for at least a year, if not longer, she says.
This is a reason why the CDC recommends vaccinations for people who have had a COVID-19 infection as well as for those who have not.
Vaccine Protection Against Variants Of The Virus
It is normal for a virus to change. Different variants of the coronavirus SARS-CoV-2 have been found all over the world. Since there are only minimal differences between the variants and the original virus, the vaccine will not immediately become ineffective. Even if a vaccine is slightly less effective against a variant, it can still offer protection against serious illness and death.
When variants of the virus occur, they will be subjected to research at the national and international levels to determine how they respond to the vaccines.
RIVM is also conducting research on variants of the coronavirus SARS-CoV-2. Read more about that research: Variants of the coronavirus SARS-CoV-2.
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What Can We Do In The Meantime
Its critical that as many people as possible get their primary vaccination shots, Dr. Meyer says. In December 2021, the CDC endorsed a recommendation to choose the Pfizer-BioNTech or Moderna vaccines, in response to concerns over rare blood clots associated with Johnson & Johnsons shot.
The good news is that Pfizer and Moderna made their mRNA vaccines easy to update, Dr. Meyer says. It just has to be tweaked a little bit, like having a computer code that needs a couple of minor edits. Its relatively easy to build. Its also important to follow the CDCs recommendations on booster shots.
The hope is that the case rate will go down and more people will be less likely to be exposed. That advice is especially important with the Delta and Omicron variants, which have proven to be more contagious than previous variants, prompting the CDC to issue stricter guidelines calling for everyonevaccinated or notto wear masks indoors in areas of high transmission.
Even if Delta and Omicron go away, I think those preventive measures will become even more important as the year passes, because potentially your immunity is going to wane over time, Dr. Meyer says.