Vaccines are the most effective preventive measure against COVID-19 and the only solution to end the pandemic.
Effective vaccines have been brought to market at an unprecedented rapid pace.
In late 2020, government health organizations in various countries around the world began vaccinating against COVID-19.
Six vaccines are now in use.
This vaccine was the first whose formulation was fixed. Even experts were surprised at the speed of its development. According to creditable media reports, the U.S. pharmaceutical company Moderna already had the formula for its mRNA-1273 vaccine ready on January 13, three days after the Sars-CoV-2 genome was published.
As the name suggests, this is a so-called mRNA vaccine. In this process, synthetically produced RNA fragments of the virus are used to give the body those instructions that enable it to produce a protein that mimics a subset of the virus. This is recognized by the immune system, which reacts and produces antibodies and T cells. If the real coronavirus appears, the defence system is equipped and can prevent infection.
In the Phase 3 study of more than 30,000 subjects, the vaccine (given in two doses four weeks apart) was 94.5 percent effective in protecting against COVID-19, specifically the severe course of infection. However, the vaccine was slightly more effective in younger groups of people than in the elderly, who are the primary target.
Compared to the Biontech/Pfizer vaccine, the Moderna vaccine caused side effects in more people, which mainly included pain at the injection site and flu-like symptoms, but these subsided relatively quickly. However, there is also an advantage compared to the Biontech/Pfizer vaccine: the Moderna vaccine, which is already licensed and vaccinated in the U.S., can be stored at minus 20 degrees Celsius for up to six months and is considered not to require minus 70 degrees like the Biontech/Pfizer vaccine.
FDA factsheet: https://www.fda.gov/media/144638/download
It is the big winner in the global race: The NT162b2 vaccine from the pharmaceutical companies BioNTech and Pfizer was the first to clear the approval hurdle in several countries and is already being used on a massive scale: more than two million doses have already been vaccinated.
As with Pfizer’s vaccine, NT162b2 is an mRNA vaccine: The vaccine gives cells the instructions they need to produce a protein that mimics part of the virus. This leads to the immune response.
The data from the pivotal Phase 3 trial involving nearly 44,000 subjects, half of whom received the vaccine and half a placebo, were impressive. The vaccine, two doses of which are administered three weeks apart, offered an efficacy of around 95 percent and also gave protection to older people.
The side effects were limited: pain at the injection site and flu-like symptoms, which subsided after one to two days. Caution is advised, however, for people who are prone to anaphylactic shock.
The main problem with NT162b2 is storage: the drug must be shipped and temporarily stored at minus 70 degrees; at normal refrigerator temperatures, it has a shelf life of five days. However, new data are expected here that could extend this period.
FDA factsheet: https://www.fda.gov/media/144414/download
This vaccine has a key role to play in the global fight against the corona pandemic. This is because the ChAdOx1 nCoV-19 vaccine from Oxford University and the pharmaceutical company AstraZeneca is inexpensive, can be produced in large quantities and does not require any special cooling. However, due to problems with trials, its approval has been delayed somewhat. But now ChAdOx1 nCoV-19 has been approved in the UK and India.
The vaccine is a so-called vector vaccine and consists of a genetically modified chimpanzee cold virus, with which genetic material from Sars-CoV-2 is introduced into human cells as a vector. This vector principle was also used in the Ebola vaccine.
The efficacy of the vaccine is still controversial: protection of around 90 percent was achieved when a half dose was administered followed by a full dose at intervals of one month. The dosing regimen that was actually intended achieved only 62 percent efficacy.
AstraZeneca CEO, Pascal Soriot, announced recently that it appears that a formula has now been found that promises efficacy similar to that of the mRNA vaccines,, although he did not give specific data. He did, however, announce a publication on the subject in the near future. So far, no serious side effects have occurred in 40,000 test subjects – the illnesses that caused a brief interruption of the Phase 3 trial were not related to the vaccine.
In the UK, the vaccine received emergency approval at the end of December 2020 and vaccinations began from January 4. What is special about the British vaccination strategy in connection with ChAdOx1 nCoV-19 is that, due to the scarcity of the vaccine, the aim is to (partially) immunize as many people as possible with an initial dose first.
Second dose only after three months
This should ensure protection against a severe course of the disease as quickly as possible. The second dose should then only be administered after three months, which is supported by independent experts in view of the infection figures. It is assumed that a later administration of the “booster”, i.e. the second partial vaccination, should not be a problem and could possibly even increase effectiveness.
FDA factsheet not yet available
Johnson & Johnson’s vaccine is administered as a single dose, unlike the two-dose coronavirus vaccines from Pfizer, Moderna and AstraZeneca.
Johnson & Johnson’s vaccine is the result of decades of research into adenovirus-based vaccines. In July, the first was approved for general use – a vaccine against Ebola, also produced by Johnson & Johnson. The company is also conducting trials of adenovirus-based vaccines for other diseases, including H.I.V. and Zika. Some other coronavirus vaccines are also based on adenoviruses, such as the one developed by Oxford University and AstraZeneca.
In a study of 43,783 participants in the U.S., Latin America and South Africa, the vaccine prevented about 66% of COVID-19 cases. The company found evidence of some immunity in participants two weeks after vaccination, which appeared to strengthen over time. The vaccine also protected against 85% of moderate-to-severe COVID-19 cases – the kind that would cause someone to seek medical attention – and has so far provided complete protection against death from COVID-19.
Side effects reported in association with Janssen COVID-19 vaccine include: Injection site reactions: pain, redness of the skin, and swelling and General side effects: Headache, feeling very tired, muscle pain, nausea, and fever.
FDA factsheet: https://www.fda.gov/media/146305/download
The Russian vaccine Sputnik V, which like Oxford University’s and manufacturer AstraZeneca’s AZD1222 vaccine is based on adenoviruses, apparently achieves the better protective efficacy, which is said to be more than 95%, according to a press release from the state direct investment fund RDIF.
The SARS-CoV-2 pandemic has accelerated the development of novel vaccines previously classified as experimental. These include AZD1222 from manufacturer AstraZeneca and Sputnik V from the Gamaleja Institute of Epidemiology and Microbiology in Moscow.
Both vaccines use adenoviruses as vectors to deliver the genes for the spike protein into the muscle cells, where the actual vaccine is then produced. The process is innovative. Adenoviruses have only been used as gene delivery vehicles in gene therapy based on a single application. Vaccinations often require multiple doses.
Since the immune system can also produce antibodies against the adenoviruses after the first vaccination, the effect of the second dose may be weakened if the immune system eliminates the viruses before they infect the target cells.
The Russian researchers anticipated the risk of antibody formation against the vector and therefore selected 2 different viruses. The vaccine for the first dose is based on a type 26 adenovirus (rAd26). For the second dose, type 5 adenovirus (rAd5) was used. This could explain why the high protective efficacy in the ongoing Phase 2/3 study was higher than in the study conducted by the manufacturer AstraZeneca.
China approved Sinopharm vaccine for general use on December 31,2020. Also approved in the UAE.
Even before official approval, some 4.5 million doses of the vaccine had been administered in China, particularly to healthcare workers or employees of state-owned enterprises. Now the authorities have given official approval to the first corona vaccine, the vaccine from state-owned Sinopharm.
According to Sinopharm, the vaccine achieved 79 percent efficacy in trials. It is administered in two doses. Vaccines from Pfizer/BioNTech and Moderna achieved an average efficacy of 95 and 94 percent, respectively. Unlike these vaccines, the Chinese vaccine does not use genetic engineering. Instead, it is based on the classical method of triggering an immune response by killing corona viruses.
So far, international confidence in Chinese vaccines has been largely lacking, in part because few test results have been published. Observers assume that China will have to make more study data available in order to gain confidence.
Date: March 19, 2021