What is the latest in COVID-19 vaccine advances? Can currently authorized vaccines protect against newly emerging SARS-CoV-2 variants? In this Hope Behind the Headlines feature, we examine these and other questions.
New, and possibly more contagious, variants of SARS-CoV-2 — which is the virus that causes COVID-19 — are emerging in countries around the world. Add to that the fact that the global number of COVID-19 cases is currently at over 95 million, and it can be difficult to remain optimistic that we will see the end of the pandemic anytime soon.
Yet scientists have not stopped working on vaccines, which are key to controlling the spread of the new coronavirus in the long run.
Stay informed with live updates on the current COVID-19 outbreak and visit our coronavirus hub for more advice on prevention and treatment.
In this Hope Behind the Headlines feature, we look at what experts have to say about whether or not currently authorized vaccines are likely to protect us against new SARS-CoV-2 variants.
We also give an overview of a promising vaccine candidate currently under trial, which has recently made the headlines.
8 COVID-19 vaccines gained authorization
Experts have explained time and again that in order to contain SARS-CoV-2 and prevent more coronavirus outbreaks in the future, vaccines are of utmost importance.
At the moment, there are eight COVID-19 vaccines with authorization in countries around the world.
So far, the Pfizer-BioNTech vaccine, which is an mRNA vaccine, has gained authorization for use in 50 countries. These include the United States, the United Kingdom, and the 27 countries that make up the European Union.
The vaccine developed by Moderna and the National Institute of Allergy and Infectious Diseases (NIAID), which is also an mRNA vaccine, is currently authorized in 36 countries. These include the U.S., the U.K., and E.U. countries.
Sputnik V, which is a viral vector vaccine developed by the Russian research institute Gamaleya, is authorized in eight countries: Algeria, Argentina, Belarus, Bolivia, Guinea, Russia, Serbia, and West Bank.
Close on its heels is the Oxford-AstraZeneca viral vector vaccine, which has gained use authorization in seven countries. These are Argentina, the Dominican Republic, El Salvador, India, Mexico, Morocco, and the U.K.
Other vaccines that have gained authorization in certain countries are:
- Covishield, a viral vector vaccine authorized in India
- Covaxin, an inactivated vaccine authorized in India
- the Sinopharm vaccine, also inactivated, which is authorized in six countries, including China, Egypt, and the United Arab Emirates
- the Sinovac vaccine, also inactivated, which is authorized in China, Indonesia, and Turkey
At a global forum held on January 15, 2021, Dr. Tedros Adhanom Ghebreyesus — the World Health Organization’s (WHO) director-general — said:
“The development and approval of several safe and effective vaccines less than a year after this virus was isolated and sequenced is an astounding scientific accomplishment.”
The U.K. has been enforcing new lockdowns in the face of ever-increasing cases of COVID-19. These rising numbers may be due to a new, and seemingly more infectious, variant of SARS-CoV-2.
South Africa and Brazil have also reported the emergence of new variants that have led to some concern.
One of the main questions that people around the world are asking in relation to emerging variants of SARS-CoV-2 is this: Will COVID-19 vaccines be effective against them?
So far, specialists and the pharmaceutical companies that produce currently available vaccines have expressed optimism that the vaccines will be effective against emerging variants and strains.
When speaking to Medical News Today earlier this month, both Pfizer and the NIAID declared that there is no reason to suspect that their vaccines would not work against the SARS-CoV-2 variant identified in the U.K.
“At present, NIAID scientists believe that the SARS-CoV-2 vaccines supported by Operation Warp Speed will provide protection against SARS-CoV-2 [U.K. variant], including […] Moderna and Pfizer-BioNTech COVID-19 vaccines authorized for emergency use by the U.S. Food and Drug Administration [FDA].”
Both Pfizer-BioNTech and Moderna-NIAID, whose vaccines are currently authorized for use in the U.S. and U.K., offer mRNA vaccines. These contain genetic information from the virus.
Our cells then make the viral Spike protein encoded in this information and present it to our immune system. This, in turn, allows our immune system to “learn” to fight off the virus, which will equip us for future infections with SARS-CoV-2.
According to experts, mRNA technology is adaptable enough that, in theory, scientists could easily “tweak” mRNA vaccines so as to ensure effectiveness against emerging variants or strains of a virus.
Dr. Uğur Şahin, the CEO of BioNTech, has declared that the Pfizer-BioNTech vaccine should work against different variants of SARS-CoV-2, against which his colleagues have already tested the vaccine. He has also noted that, in any case, their vaccine is easily adaptable.
Other scientists have also noted that at least some of the COVID-19 vaccines that have gained authorization around the world should be adaptable so as to remain effective against emerging variants of SARS-CoV-2.
In relation to the variant that emerged in South Africa, Dr. Julian W. Tang — a clinical virologist from the University of Leicester in the U.K. — has commented:
“Even if the South African variant becomes more widespread and dominant, the mRNA (Pfizer-BioNTech and Moderna) and adenovirus-vectored (Oxford-AstraZeneca and Russian Sputnik V) vaccines can be modified to be more close-fitting and effective against this variant in a few months.”
“Meanwhile,” he added, “most of us believe that the existing vaccines are likely to work to some extent to reduce infection/transmission rates and severe disease against both the U.K. and South African variants — as the various mutations have not altered the S protein [which helps the virus gain entry into healthy cells] shape that the current vaccine-induced antibodies will not bind at all.”
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Although some vaccines have already gained use authorization in various countries, there are still many vaccine candidates currently undergoing clinical trials.
Some of the candidates in late-stage trials are showing promise, offering hope that more vaccines may become available around the world by the end of 2021.
A top contender is the vaccine candidate developed by pharmaceutical company Johnson & Johnson. This candidate is also known as the Janssen COVID-19 vaccine candidate.
Johnson & Johnson’s experimental viral vector vaccine uses a modified adenovirus, or a common cold virus, as the vaccine candidate “base.” This carries the gene for the SARS-CoV-2 Spike protein.
Unlike some of the vaccines that have already gained use authorization, the company are testing this vaccine candidate as both a single-dose and a two-dose regimen to create immunity.
The Janssen COVID-19 vaccine candidate was already showing some promise in early trials, though these briefly paused in October 2020 due to one of the trial participants developing “unexplained illness.”
Trials have since resumed, and the company have recently made available the interim results from phases 1 and 2.
These results indicate that the vaccine candidate was well tolerated by participants overall, suggesting that it is safe. The vaccine candidate also appeared to induced an immune response in those who received it, suggesting that it may also be effective against SARS-CoV-2.
The phase 3 trial data should also be available by the end of January, according to a Johnson & Johnson statement. Once these data are available, the company are hoping to file for FDA emergency use authorization.
According to a recent New York Times report, Dr. Paul Stoffels — the chief scientific officer at Johnson & Johnson — has commented that “hopefully somewhere in March [the company will] be able to contribute” to vaccination efforts in the U.S.
For live updates on the latest developments regarding the novel coronavirus and COVID-19, click here.
How do COVID-19 vaccines compare with other existing vaccines?
The novelty of the COVID-19 vaccines may seem daunting for some, and it is natural for questions to arise on their effectiveness. In this feature, we examine the difference between effectiveness and efficacy, compare the COVID-19 frontrunner vaccines to other vaccines, such as the flu shot, and compare their safety considerations.
All data and statistics are based on publicly available data at the time of publication. Some information may be out of date. Visit our coronavirus hub and follow our live updates page for the most recent information on the COVID-19 pandemic.
As Pfizer/BioNTech roll out their COVID-19 vaccine throughout the United Kingdom and the United States, the world wonders how effective it will be.
Looking at the three leading vaccines that we have previously reported on, Pfizer/BioNTech boasts 95% efficacy, the Oxford/AstraZeneca vaccine candidate has an average of 70% efficacy, while the Moderna vaccine candidate reportedly has 94.1% efficacy.
But what does this say about their effectiveness? And how does it compare with vaccines against the flu, polio, and measles?
Stay informed with live updates on the current COVID-19 outbreak and visit our coronavirus hub for more advice on prevention and treatment.
Firstly, it is worth noting that “effectiveness” and “efficacy” are not the same. Despite news outlets frequently using them interchangeably, efficacy refers to how a vaccine performs under ideal lab conditions, such as those in a clinical trial. In contrast, effectiveness refers to how it performs in the real world.
In other words, in a clinical trial, a 90% efficacy means that there are 90% fewer cases of disease in the group receiving the vaccine compared with the placebo group.
However, the participants chosen for a clinical trial tend to be healthier and younger than those in the general population, and they generally have no underlying conditions. Furthermore, researchers do not normally include certain groups in these studies, such as children or pregnant people.
So, while a vaccine can prevent disease in a trial, we might see this effectiveness drop when administered to the wider population.
However, that is not in itself a bad thing.
Vaccines do not need to have high effectiveness to save thousands of lives and prevent millions of disease cases.
The popular flu shot, for example, has an effectiveness of 40–60%, according to the Centers for Disease Control and Prevention (CDC).
However, during 2018–2019, it prevented around “4.4 million influenza illnesses, 2.3 million influenza-associated medical visits, 58,000 influenza-associated hospitalizations, and 3,500 influenza-associated deaths.”
It is also worth noting that the flu vaccine’s effectiveness varies from season to season, due to the nature of the flu viruses circulating that year. Determining the precise rate of effectiveness can be challenging.
Finally, it bears mentioning that the number of doses can also improve effectiveness for some vaccines. For the flu shot, two doses of the vaccine instead of one can offer a protection boost, but this benefit is limited to only a few specific groups, such as children or organ transplant recipients.
The booster dose does not seem to benefit people over the age of 65 or those with a compromised immune system.
By contrast, as we will see below, for vaccines, such as the ones against polio and measles, a higher number of doses is required to achieve peak effectiveness.
The vaccine against polio can be up to 100% effective. According to the CDC, “Two doses of inactivated polio vaccine (IPV) are 90% effective or more against polio; three doses are 99% to 100% effective.”
However, experts recommend IPV in four doses. The CDC recommend that children take one dose of the vaccine at 2 months old, another dose at 4 months old, a third dose at 6–18 months old, and a final fourth dose at 4–6 years old.
These four doses combined yield 99–100% effectiveness.
The IPV vaccine protects against poliomyelitis, a disease caused by the poliovirus, which can trigger an infection in a person’s brain and spinal cord, causing paralysis.
The MMR vaccine, which protects against measles, mumps, and rubella, can be up to 97% effective at preventing measles when administered in two doses.
One dose is approximately 93% effective, according to the CDC.
The CDC recommend administering the first dose at “12 through 15 months of age, and the second dose at 4 through 6 years of age.”
When it comes to new vaccines, the issue of safety is understandably on everyone’s minds.
The question “how safe is this vaccine?” can be translated as “what is the risk of developing side effects from this vaccine?” And, in answering this query, it is important to note there is no drug — not even the most common painkiller — that is entirely free from side effects.
Scientists have broken down the side effects that they expect to occur with the BioNTech vaccine — currently the only one with approval for use in the U.K. and the U.S. — into “very common,” “common,” and “uncommon.”
Very common side effects, which may affect more than 1 in 10 people, include:
- pain at the injection site
- tiredness
- headache
- muscle pain
- chills
- joint pain
- fever
The common side effects, which may affect up to 1 in 10 people, are:
- injection site swelling
- redness at the injection site
- nausea
Uncommon side effects, which may affect up to 1 in 100 people, include enlarged lymph nodes or feeling unwell.
By comparison, the CDC list the following side effects for the flu shot as common:
- soreness and redness, swelling, or both, from the shot
- headache
- fever
- nausea
- muscle aches
Occasionally, they add, the flu shot may cause fainting, like any other injections. The CDC recommend that everyone take the flu vaccine, except for children younger than 6 months of age or those with severe allergies to the flu vaccine or any ingredient in the vaccine.
Some studies have found a slight risk of Guillain-Barré syndrome after flu vaccination, while other studies found no association. For those that did find such a likelihood, this risk was 1–2 in 1,000,000 people.
For MMR, the side effects listed as common by the CDC are:
- sore arm from the shot
- fever
- mild rash
- temporary pain and stiffness in the joints
Rarely, the vaccine may trigger febrile seizures, swelling in the cheeks or neck, or a temporary low platelet count in the blood. However, none of these are life threatening or have long-term effects.
For polio, the CDC note that “A sore spot with redness, swelling, or pain where the shot is given can happen after a polio vaccine.” In addition, “As with any medicine, there is a very remote chance of a vaccine causing a severe allergic reaction, other serious injury, or death.”
Since rolling out the BioNTech vaccine in the U.K., two recipients — who had a history of serious allergies — developed allergic reactions.
This prompted regulators to recommend people who have a history of significant allergic reactions do not have the COVID-19 vaccine.
While erring on the side of caution is preferable in the early stages of rolling out a vaccine, it is worth noting that all vaccines — including the ones for polio, flu, and measles — have a risk of triggering severe allergic reactions.
This risk stands at around 1 in 900,000 people.
With the COVID-19 vaccine and vaccine candidates, the safety data we have so far come from tens of thousands of people receiving the vaccine in the Pfizer/BioNTech, Moderna, and Oxford/AstraZeneca trials.
So, the safety information we can obtain based on this number of participants is enough for regulators to decide whether a vaccine is safe enough to license. However, it may not be enough to detect rare events that could affect 1 in 100,000 people, for example.
As Dr. Charlie Weller, Head of Vaccines at the Wellcome Trust in London, U.K., points out, “Much more data would be needed to determine if there is any relationship between the vaccine and these [allergic] reactions. Guidance would then be issued to those who might be at risk.”
“As vaccine rollout is just beginning, many unanswered questions remain. Ongoing monitoring will help us identify any consistent patterns of adverse events. As is normal for any vaccine, close and continued monitoring for safety and efficacy data as it is delivered will be essential.” – Dr. Charlie Weller
“For the general population, this does not mean that they would need to be anxious about receiving the vaccination,” adds Prof. Stephen Evans, Professor of Pharmacoepidemiology at the London School of Hygiene & Tropical Medicine.
For live updates on the latest developments regarding the novel coronavirus and COVID-19, click here.
Fonte: Medical News Today / Tradução Google
As informações e sugestões contidas neste blog são meramente informativas e não devem substituir consultas com médicos especialistas.
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