Quick Guide: COVID-19 Vaccines In Use And How They Work

Source : bioworld

Dozens of coronavirus vaccines entered clinical trials during 2020 and now, a couple are authorized for emergency-use in various countries, meaning the shots can be administered to the general public while their developers still collect data on their safety & efficacy.

Should they meet all the required criteria, these vaccines might be fully approved in the future and in some places, they’ve already got been.

Here is a quick guide to the COVID-19 vaccines now in use around the world.

Pfizer-BioNTech Vaccine

The vaccine developed-by Pfizer & German biotechnology company BioNTech is 95% effective at preventing COVID-19, study found.

The vaccine is administered in 2 doses, given 3 weeks apart and it must be stored at -94 degrees Fahrenheit (-70 degrees Celsius).

On 11 December 2020, the Pfizer-BioNTech vaccine became the first COVID-19 vaccine to be authorized for emergency use by U.S. Food & Drug Administration (FDA).

Several other countries have authorized the vaccine for emergency use, including the U.K., Argentina, Chile & Singapore and the European Union followed suit on December 21, The New York Times reported.

Bahrain, Canada, Saudi Arabia & Switzerland have fully approved the vaccine. On January 25, Australia gave the vaccine “provisional approval” for use in people aged 16 & over, The Associated Press reported.

The shot uses a molecule, called mRNA as its base. A molecular cousin of DNA, mRNA contains instructions to produce specific proteins.

In this case, mRNA in the vaccine codes for the coronavirus spike protein, a structure that sticks-off the virus’s surface and is used to infect human cells.

Once inside the body, vaccine instructs human cells to produce this protein and the immune system learns to recognize & attack it.

Moderna Vaccine

The vaccine developed-by U.S. biotech company, Moderna and the National Institute of Allergy & Infectious Diseases (NIAID), also uses mRNA as its base and is estimated to be 94.5 percent effective at preventing COVID-19.

Like the Pfizer-BioNTech vaccine, it is delivered in 2 doses, but the doses are given 4 weeks apart, instead of 3.

Another difference is that the Moderna vaccine can be often stored at -4 F (minus 20 C), instead of requiring deep-freezing, like the Pfizer shots.

The FDA authorized the Moderna vaccine for emergency-use on December 18 and Israel & the European Medicines Agency, an agency of the European Union, both authorized the shots for emergency use in January, consistent with The Times.

Canada fully approved the vaccine on December 23.

Oxford- AstraZeneca Vaccine

The vaccine developed-by Oxford University & pharmaceutical company AstraZeneca is estimated to be about 70 percent effective at preventing COVID-19 that said in clinical trials, adjusting the dose seemed to boost this efficacy.

In people given 2 full-size doses, spaced 28 days apart, the vaccine was about 62 percent effective, in those given a half-dose followed by a full dose, the vaccine was 90 percent effective, consistent with early analyses.

However, clinical trial participants who got half-doses did so by mistake and a few scientists have questioned: whether those early results are representative.

The U.K. & Argentina authorized the Oxford-AstraZeneca vaccine for emergency-use in late December and India & Mexico authorized the vaccine for emergency-use in January, consistent with the Times.

The EU’s European Medicines Agency authorized the vaccine for emergence-use in adults on January 29, The Associated Press reported. Canada approved the vaccine on February 26, CTV News reported.

The shots contain a weakened-version of adenovirus, a common cold virus that naturally infects chimpanzees.

Scientists modified the virus so it can’t replicate in human cells, then added genes that code for the coronavirus spike protein.

Inside the body, the vaccine enters cells & delivers these spike protein genes, which the cells use to produce the spike protein itself. The presence of spike proteins triggers an immune response.

Johnson & Johnson

The vaccine developed-by Johnson & Johnson’s Janssen showed a 72 percent overall efficacy rate in the U.S. & 64 percent in South Africa, where a highly-transmissible coronavirus variant is causing most new cases, consistent with an FDA analysis conducted in February, the Times reported.

In terms of preventing severe disease, single-shot vaccine showed 86 percent efficacy in the U.S. & 82 percent in South Africa and in both locations, the vaccine showed 100 percent efficacy against hospitalization & death.

It means that no one given the vaccine in the clinical trials died from COVID-19 or required hospitalization for the disease, when assessed at 28 days post-vaccination.

On February 25, following the FDA analysis, Bahrain became the first country to authorize the vaccine for emergency-use. The U.S. cleared the vaccine for emergency use on February 27.

Similar to the vaccine developed-by University of Oxford & AstraZeneca, Johnson & Johnson shot contains a weakened-version of a common cold virus, called as an adenovirus.

Scientists genetically-altered the adenovirus, named ad26, so it can no longer infect human cells, then added genes that code for the coronavirus spike protein.

Once inside the body, the vaccine trains the immune system to acknowledge the spike protein and target the coronavirus for destruction.

Janssen used similar strategy to develop its existing Ebola vaccine. The shot can be stored for months at normal refrigerator temperatures.

Sinopharm (Beijing Institute of Biological Products)

Sinopharm, state-owned China National Pharmaceutical Group & Beijing Institute of Biological Products developed a vaccine from an inactivated coronavirus, meaning a modified-version of SARS-CoV-2 that can’t replicate.

In late December, Sinopharm announced that the vaccine, BBIBP-CorV, is more than 79 percent effective, consistent with preliminary data from late-stage clinical trials, that said, the company hasn’t published said data.

In summer of 2020, China gave Sinopharm authorization to vaccinate construction workers, diplomats & students with one among its two COVID-19 vaccine candidates, including BBIBP-CorV.

Nearly one million people received the vaccines by-November, consistent with the company’s chairman.

The United Arab Emirates authorized BBIBP-CorV for emergency-use in September, then fully approved the vaccine in December.

Bahrain & China also fully approved the vaccine in December and Egypt authorized it for emergency-use in January 2021, the Times reported.

The vaccine is given in 2 doses spaced 3 weeks apart.

Sinopharm (Wuhan Institute of Biological Products)

Sinopharm’s second vaccine candidate, developed-by the Wuhan Institute of Biological Products, also uses an inactivated coronavirus as its base.

The vaccine authorized for emergency-use in China & the U.A.E., but little is known about its efficacy.

CanSino – Beijing Vaccine

CanSino Biologics, in collaboration with Beijing Institute of Biotechnology, developed a COVID-19 vaccine using a weakened-adenovirus, but one that naturally infects humans, not chimpanzees.

Late-stage clinical trials with the vaccine are still ongoing and its efficacy isn’t yet known. The shot is given in a single dose.

In June 2020, CanSino vaccine was given approval to be used by China’s military, consistent with Reuters.

CoronaVac By Sinovac Biotech

The Chinese company Sinovac Biotech developed a vaccine from an inactivated-version of SARS-CoV-2. The vaccine called CoronaVac, is given in 2 doses 14 days apart. China authorized the vaccine for emergency-use in July.

Estimates vary as-to how well the vaccine protects against COVID-19 and an official estimate hasn’t yet been issued.

One clinical trial in Brazil suggested, the vaccine was about 78 percent effective in one small subgroup of patients, but across all people, the efficacy could be closer to 63 percent, consistent with Estadão, a Brazilian news outlet.

On January 12, researchers from Butantan Institute, the biologic research center, where the trials were conducted, announced that the efficacy rate is 50.4 percent overall, based-on the latest data, BBC News reported.

Bharat Biotech Vaccine

The Indian company Bharat Biotech, along with the Indian Council of Medical Research and the National Institute of Virology developed a vaccine-from an inactivated coronavirus called Covaxin, the Times reported.

The vaccine is given in 2 doses, spaced 4 weeks apart and has been authorized for emergency-use in India. It is efficacy hasn’t been publicly reported.

Sputnik V By Gamaleya Research Institute

The Russia Ministry of Health’s Gamaleya Research Institute developed a coronavirus vaccine candidate called Sputnik V, in reference to the world’s first artificial satellite, launched during the space race.

The vaccine contains 2 common cold viruses or adenoviruses, that modified in order that they do not replicate in humans. The modified viruses also contain genes that code for the coronavirus spike protein.

In November, Russia announced that the vaccine is more than 91.4 percent effective in preventing COVID-19, consistent with early data from clinical trials.

On February 2, scientists reported that the vaccine has 91.6 percent efficacy, based-on preliminary data from a late-stage trial published in the Lancet.

Russia began offering the vaccine to its citizens as a part of a mass vaccination campaign in November 2020, consistent with The New York Times.

Russia had already approved the vaccine for limited-use in August, when little data from human trials was available.

Since November, Belarus, Argentina & Serbia have also authorized the vaccine for emergency-use, the Times reported.

On January 15, Paraguay also authorized the vaccine for emergency use, Reuters reported.

Vector Institute Vaccine

In October 2020, Russia granted regulatory approval to a second vaccine, one developed-by Vector Institute, a Russian biological research center, consistent with CNBC.

The vaccine contains coronavirus peptides, which are small-portions of proteins found in the virus. Like Sputnik V, the vaccine earned approval in Russia before large-scale clinical trials had been conducted.

As of now, its efficacy remains unknown.

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