New Variants Change The Herd
Even as vaccine roll-out plans face distribution and allocation hurdles, new variants of SARS-CoV-2 are sprouting up that might be more transmissible and resistant to vaccines. Were in a race with the new variants, says Sara Del Valle, a mathematical and computational epidemiologist at Los Alamos National Laboratory in New Mexico. The longer it takes to stem transmission of the virus, the more time these variants have to emerge and spread, she says.
Brazil began widespread distribution of Sinovac Biotechs CoronaVac vaccine in January.Credit: Rodrigo Paiva/Getty
Theres another problem to contend with as immunity grows in a population, Ferrari says. Higher rates of immunity can create selective pressure, which would favour variants that are able to infect people who have been immunized. Vaccinating quickly and thoroughly can prevent a new variant from gaining a foothold. But again, the unevenness of vaccine roll-outs creates a challenge, Ferrari says. Youve got a fair bit of immunity, but you still have a fair bit of disease, and youre stuck in the middle. Vaccines will almost inevitably create new evolutionary pressures that produce variants, which is a good reason to build infrastructure and processes to monitor for them, he adds.
How Many People Do We Need To Vaccinate Against Covid
The Delta variant of SARS-CoV-2 has rapidly come to dominate in the Covid-19 pandemic.
getty
The rise of the Delta variant means the race to vaccinate the entire global population has taken on a new urgency.
The Delta variant of SARS-CoV-2 is now by far the most widespread variant in the US and around the world.
Data from the Nextstrain Genomic Epidemiology of Novel Coronavirus Global Subsample showing the … relative frequencies of all major SARS-CoV-2 variants around the world as of July 28, 2021. Over just four months, the Delta variant has almost completely replaced the previously dominant strain .
Nextstrain.org
Delta is also considerably more transmissible than the other widespread SARS-CoV-2 variants. This is important because transmissibility is directly proportional to the basic reproduction number, R0, from which mathematical epidemiologists derive the number of people who have to be vaccinated to reach herd immunity.
Delta raised the threshold for herd immunity, and we now have to vaccinate many more people than was previously required to contain Covid-19
How many more? The basic formula for the immune threshold is
Threshold = 1-1/R0.
How Likely Is It That 235 Million Americans Will Be Fully Vaccinated Within A Year Or So Of Vaccines Being Rolled Out
Vaccine uptake depends on a range of factors, from access to healthcare to distribution to personal beliefs and values on vaccinations.
Influenza vaccination uptake was just under 64 percent among minors for the 2019-20 flu season, and just over 48 percent among adults. Both were slightly up from previous seasons, but well short of the necessary numbers that would be required to eradicate SARS-CoV-2.
Having personal experience of an infection through a friend’s or loved one’s suffering does appear to make a difference in uptake for other types of vaccines. It’s possible a sufficient media campaign for a COVID-19 vaccine, along with easy access to mobile vaccinations clinics, could nudge vaccination uptake in most accessible places around the globe past 70 percent by December 2021.
Though with targeted campaigns being waged by anti-vaccination groups through social media, it’s hard to say which way vaccination rates might go.
In July 2020, the US reserved 100 million doses of the Pfizer vaccine as part of a US$1.95 billion deal, which will provide an initial 50 million vulnerable citizens and essential workers with a chance of immunity. With other nations bidding for vaccines and production speed limited, it’s hard to say how soon additional doses will be rolled out.
The best chance of success at eradicating SARS-CoV-2 will more than likely entail a mix of vaccination, social distancing, and the continued wearing of masks in public spaces for the foreseeable future.
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What Can I Expect When I Get The Vaccine
You might feel nervous about getting the vaccine, which is normal.
A fully trained vaccinator will give you the vaccine in your upper arm, and it will be over very fast. You will then need to stay for at least 15 minutes so we can make sure you do not have an immediate reaction.
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What Does Fully Vaccinated Mean

According to CDC guidelines, you are fully vaccinated when it has been:
- Two weeks after your second dose in a two-dose series, such as the Pfizer or Moderna vaccines.
- Two weeks after a single dose of the Johnson & Johnson vaccine. However, data from clinical trials are clear that there is further improvement four weeks after the single-shot vaccine, especially for preventing severe COVID-19 or having asymptomatic infection. For this reason, Johns Hopkins Medicine recommends four weeks after the single-dose vaccine to be considered fully vaccinated.
If you dont meet these requirements, you are not fully vaccinated.
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Will We Need An Omicron
If two doses of the Moderna or Pfizer COVID-19 vaccine are not enough to guard against omicron, would we need a variant-specific booster to restore protection? According to Fauci, “At this point, there is no need for a variant-specific booster.”
But getting people to upgrade from two doses to three will take additional effort: The CDC website says more than 210 million Americans right now are “fully vaccinated” with the Moderna, Pfizer or Johnson & Johnson vaccines. That’s 63.3% of the total US population. However, only 83.5 million in the US have received a booster — 39.7% of the so-called fully vaccinated, or a little more than 25% of the total US population.
Moderna has said it is studying an omicron-specific vaccine, as well as a multivalent shot that could protect against the alpha and delta strains, but clinical trials aren’t expected to start until next year.
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Can Children Receive A Covid
The Centers for Disease Control and Prevention now recommends a COVID-19 vaccine for children ages 5 and older. Johns Hopkins Medicine encourages all families to have eligible children vaccinated with the COVID-19 vaccine. Currently, Pfizers vaccine is the only approved COVID-19 vaccine for children.
Read more about what parents need to know about the COVID-19 vaccine.
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What Percentage Of People Need To Be Vaccinated To Reach Herd Immunity
ST. PAUL, Minn. For all the progress in getting people vaccinated against COVID-19, about 40% of Americans remain hesitant about getting the shot. Thats from a recent CBS News poll.
It had us wondering, what percentage of people vaccinated must we hit to reach herd immunity? And what happens if we dont reach that number? Good Question. Jeff Wagner learned the answer is a work in progress.
While out on a stroll around Lake Como, friends Darnell Steppan and Heather Doarn carried an air of confidence knowing theyve been fully vaccinated.
But I still mask up. I mean its a respect thing, said Steppan.
I went into the grocery store for the first time in a year yesterday, added Doarn.
Those ladies are two of the roughly 140 million Americans who took a shot in the arm to fight COVID-19.
Thats about 42% of the country, an achievement in itself, but still far from the lofty goals medical experts are setting.
What is that target number for herd immunity?
You know what, no one really knows that number, said Dr. Michael Osterholm, director for the Center for Infectious Disease Research and Policy at the University of Minnesota. At this point, many of us believe that that number is close to 100%, something that probably isnt achievable.
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Is there a number where people can expect things to somewhat feel normal again?
What happens if we dont hit 80%?
What Has Johnson & Johnson Said About A Second Booster Shot
A study of 69,000 health care workers released in December by the South African Medical Research Council found that, for those who already received the J& J vaccine, Ad26.COV.2, a booster given six to nine months later raised their odds against hospitalization from 63% to 85%.The research was conducted between mid-November and mid-December 2021, when the omicron variant represented 98% of all confirmed COVID cases in South Africa, suggesting the vaccine offers strong protection against the highly contagious strain.
“This adds to our growing body of evidence which shows that the effectiveness of the Johnson & Johnson COVID-19 vaccine remains strong and stable over time, including against circulating variants such as omicron and delta,” Dr. Mathai Mammen, global head of Janssen Research & Development, a pharmaceutical subsidiary of Johnson & Johnson, said in a statement.
For more on COVID-19, here’s how the new omicron variant is different from the delta strain, what to know about the Moderna COVID booster and how to choose which booster shot to get.
The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.
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Why Doesn’t ‘fully Vaccinated’ For Covid
While the CDC pivots away from the term “fully vaccinated,” more organizations and governments are requiring boosters.
The CDC is replacing the term “fully vaccinated” to “up to date.”
Despite new data showing the effectiveness of boosters and the skyrocketing number of COVID-19 cases due to the more infectious omicron variant, the CDC has no plans to change its definition of “fully vaccinated.” The term still means two shots of the Moderna or Pfizer mRNA vaccines or one shot of Johnson & Johnson. Instead, the agency is pivoting to the more general descriptor of “up to date” to describe effective vaccine protection.
At Friday’s White House press briefing, Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, was asked by CNN, “Can you explain why the CDC is not changing the definition of ‘fully vaccinated,’ given that could potentially encourage more people to get a third shot?” The US has currently boosted 85.5 million people, or about 40% of people considered fully vaccinated.
Walensky responded: “In public health, for all vaccines, we’ve talked about being up to date for your vaccines. Every year, you need a flu shot you’re not up to date with your flu shot until you’ve gotten your flu shot for that year. … What we really are working to do is pivot the language to make sure that everybody is as up to date with their COVID-19 vaccines as they personally could be.”
Fact: As Of August 9 The Cdc Said There Had Been 8054 Vaccinated People Who Were Hospitalized Or Died Who Had Also Tested Positive For Coronavirusout Of More Than 166 Million Fully Vaccinated Americans Thats Roughly 005 Percent Additionally Cdc Director Rochelle Walensky Has Said That 995 Percent Of All Deaths From Covid
Hamer: COVID vaccines have been shown to be very powerful in preventing more severe disease and the need for hospitalization. Breakthroughs occur at a much, much lower rate than in people who are unvaccinated. The breakthroughs have been occurring more frequently with the Delta variant because of the high level of infectiousness of the Delta variant and lower protection of current vaccines against this variant. But people having breakthroughs have much more mild infection, more like an upper respiratory infection. The vaccines prevent severe disease and complications and allow people to return to a more normal state.
Assoumou: I was just at the hospital taking care of patients. I can tell you all the cases of people getting hospitalized are unvaccinated. Breakthrough cases account for much less than 1 percent. There are so many zeros before the one99 percent of people dying now of COVID are unvaccinated. And 97 percent of those hospitalized are unvaccinated. We are just not seeing large numbers of people vaccinated being hospitalized. And if you get it, for the most part it is like having a cold.
MYTH: The COVID vaccines can affect a womans fertility.
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Unvaccinated Adults Younger Less Educated
Adults who had not received any doses of the COVID vaccine differed from those who had received at least one dose of a COVID vaccine across several measures.
- They were younger, on average, than those who had been vaccinated. Roughly 75% of the unvaccinated were under age 50. Among the vaccinated, less than half were under age 50.
- They had lower levels of education, on average, than those who were vaccinated. Survey respondents who had received at least one dose were twice as likely as the unvaccinated to have a college degree or higher.
- They were much less likely than vaccinated adults to be married .
When Can I Get The Coronavirus Vaccine

Now that the Food and Drug Administration has issued emergency use authorizations for COVID-19 vaccines, vaccines are being distributed across the United States.
If you are a Johns Hopkins Medicine patient, visit our COVID-19 Vaccine Information and Updates page for current information on getting vaccinated. Your states health department website can also provide updates on vaccine distribution in your area.
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Do People Who Have Had Covid
People who have had COVID-19 and recovered should still be vaccinated.
The protection someone gains from having COVID-19 varies from person to person.
Because this virus is new, experts dont yet know how long any natural immunity might last.
This is why vaccination is so important to protect people from severe disease.
Even if you have already had COVID-19, you should still get the COVID-19 vaccine when you can.
Read more about vaccination after testing positive to COVID-19.
You should discuss any treatments you had with your doctor before you get vaccinated.
With new COVID-19 vaccine developments every day, its normal to have questions or concerns, and possibly feel hesitant about getting a vaccine. That’s why we’re providing accurate, evidence-based answers to questions about COVID-19 vaccines.
How Does Herd Immunity Work
For a contagious disease to spread, an infectious agent needs to find susceptible people to infect. If it cant, the chain of infection is interrupted and the amount of disease in the population reduces.
Another way of thinking about it is that the disease needs susceptible victims to survive in the population. Without these, it effectively starves and dies out.
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Five Reasons Why Covid Herd Immunity Is Probably Impossible
As COVID-19 vaccination rates pick up around the world, people have reasonably begun to ask: how much longer will this pandemic last? Its an issue surrounded with uncertainties. But the once-popular idea that enough people will eventually gain immunity to SARS-CoV-2 to block most transmission a herd-immunity threshold is starting to look unlikely.
That threshold is generally achievable only with high vaccination rates, and many scientists had thought that once people started being immunized en masse, herd immunity would permit society to return to normal. Most estimates had placed the threshold at 6070% of the population gaining immunity, either through vaccinations or past exposure to the virus. But as the pandemic enters its second year, the thinking has begun to shift. In February, independent data scientist Youyang Gu changed the name of his popular COVID-19 forecasting model from Path to Herd Immunity to Path to Normality. He said that reaching a herd-immunity threshold was looking unlikely because of factors such as vaccine hesitancy, the emergence of new variants and the delayed arrival of vaccinations for children.
Long-term prospects for the pandemic probably include COVID-19 becoming an endemic disease, much like influenza. But in the near term, scientists are contemplating a new normal that does not include herd immunity. Here are some of the reasons behind this mindset, and what they mean for the next year of the pandemic.
How Do Vaccines Work
Vaccines help people develop immunity to a virus or other germ. A vaccine introduces a less harmful part of that germ or something created to look or behave like it into a persons body. The bodys immune system develops antibodies that fight that particular germ and keep the person from getting sick from it. Later, if the person encounters that germ again, their immune system can recognize it and remember how to fight it off.
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Pubs Bars Nightclubs And Licensed Events
The restriction on numbers of people dancing and drinking standing up at events and venues where alcohol is served, and where people are freely mixing, has been lifted from 6 December 2021.
However, all patrons must now be fully vaccinated to enter a pub, nightclub or bar, or to attend a licensed event where alcohol is served to people who are likely to be standing and drinking. All staff working in these areas must also be fully vaccinated from 15 December 2021.