Is it worth giving the first dose of the COVID vaccine to more people? Seven keys to keep in mind

Most COVID-19 vaccines need to be given in two doses to achieve adequate protection against the coronavirus based on the clinical trials that have evaluated them. But the reality today is that access to vaccines today faces barriers because there are difficulties with mass production in laboratories and the richest countries have accumulated more doses. Faced with the problem of scarcity, England has already changed the vaccination schedule and decided to apply the first dose to more people and postpone the second as a strategy to reduce infections as soon as possible. Italy and Argentina are among the countries where health authorities are assessing the possibility of making the change.

Here are the 6 keys to understanding measurement in the midst of a pandemic that has already claimed more than 2.6 million lives worldwide. In Argentina, 88% of people over 60, who are most at risk, have yet to receive their vaccine, and experts warn the second wave of the pandemic in the country will come.

1- Have clinical trials shown that one or two doses of vaccines are needed to protect against COVID-9?

Clinical trials have demonstrated the efficacy and safety of several vaccines that are still in phase 3. The speed at which the first COVID-19 vaccines were developed was unprecedented: they were achieved in less than a year. . For example, the measles vaccine was obtained only 10 years after the discovery of the pathogen. Tests indicated that two doses are needed to achieve high protection against COVID-19 vaccines that have been approved for emergency use in Argentina, such as Sputnik V from the Gamaleya Institute of Russia and vaccines produced by the companies Pfizer / BioNTech (US-Germany), AstraZeneca (UK) and Sinopharm from China.

However, today there is a shortage of available doses of these vaccines, and there is a risk that the spread of the virus will increase again, but the population most at risk of complications and death – those over 60 – is not yet vaccinated. Then, to give protection more quickly to this risk group, the first dose can be given to more people and the second dose can be delayed until later. Another option is to give only the first dose. Although a single dose does not ensure total protection at the individual level, it has an important health impact in reducing the transmission of the virus and reducing mortality in people at risk of suffering from serious ailments, as assessed by the ministry. of the Health of the Nation.

2- Has the administration of the first dose against COVID-19 to more people been served in any country?

Yes. According to the Minister of COVID-19 Vaccine Deployment, Nadhim Zahawi, in England, they decided to postpone the second dose last September in order to vaccinate more people with the first dose. With this strategy, they have already seen significant results in reducing hospitalizations, severe cases, contagion and mortality, even among those over 80. According to the official, the first dose of vaccines reduced hospitalizations and deaths by 90% in this country. Another option is to give only the first dose. They have already inoculated 27 million people with the first dose of Pfizer / BioNTech and AstraZeneca / Oxford vaccines. Only 3 percent of the total population has been fully immunized.

3- Can all COVID-19 vaccines be included in the change to the second dose deferral schedule?

The option to change would affect some of the vaccines authorized to date. Two Canadian epidemiologists suggest in the journal New England Journal of Medicine administration of a single dose of Pfizer-BioNTech vaccine until all at-risk groups are immunized. Based on their interpretation of clinical trial data for this vaccine, the researchers claim that up to 92% immunization would be achieved within 12 days of receiving the first dose. Therefore, there would be data that would support this possibility.

In the case of the Sinopharm vaccine, the second dose should be given between 21 and 28 days after the first dose and so far it is only allowed for people under 60 years of age. In the case of Sputnik V, the second dose should be administered after 21 days. In exchange The COVISHIELD vaccine, produced by the Serum Institute of India in collaboration with the University of Oxford and AstraZeneca, supports the possibility of dose spacing. Although the manufacturer’s recommendation is to maintain an interval between doses of 4 to 12 weeks, the World Health Organization (WHO) recommends setting up an interval of 8 to 12 weeks between doses.

4- Are the different vaccines available interchangeable?

No. According to the available data – reported the Nation’s Ministry of Health, the different COVID-19 vaccines are not interchangeable. The schedule should be completed with the same vaccine that you started with. The second dose is only contraindicated when a serious complication has developed after the application of the first dose.

5- What happens if a single dose is given to more people and the second dose is not given?

The possibility of The administration of a single dose of the Covid-19 vaccine is only studied for people who have had COVID-19 in the past. People who have had COVID-19 “have developed an immunological memory after infection” and “the single dose of the vaccine will thus play a reminder role”, according to the High Authority of Health (HAS), in a recommendation which has not yet received the approval of the government. This organization recommended that people wait “beyond three months” after having COVID-19, “and preferably six months”, before injecting the single dose of the vaccine. On the other hand, in Argentina, the Health portfolio reported that the clinical and health impact of administering a single dose to already infected people is still unknown. Therefore, this change would not be adopted.

6- Why is the postponement of the second dose being considered?

Options are being explored due to lack of doses. Buenos Aires Deputy Health Minister Nicolás Kreplak reported that the province of Buenos Aires has a number of coronavirus vaccines “until Monday” next week, due to the lack of arrival of shipment of medical supplies from producing laboratories.

Buenos Aires Health Ministry Under Secretary for Information Management Leticia Ceriani said: “This is something that is definitely under discussion. In fact, there are vaccines that only have one dose. It is analyzed in different parts of the world and it seems extremely reasonable to us. There is no doubt that our main goal is to vaccinate many people with a single dose, rather than to vaccinate a few people with the full schedule ”. A few days ago, Minister of Health Carla Vizzotti also said: “It was never a question of giving a single dose, but of postponing the second dose. It is a difference. It’s not just a dose, but vaccinate more people with the first dose to vaccinate more people ”.

7-Are there any concerns about changing the vaccination schedule?

In Italy, health authorities are also assessing the possibility of a change by looking at what happened in England. Not everyone is convinced that the delayed second dose strategy is the smartest option yet.all the more so since there are no reliable data to date on the duration of the protection provided by a single administration, compared to the two doses which had been planned. Experts believe that in the case of a postponement of a few days or a few weeks, there should not be any particular risks, but things could get complicated in the case of long postponements. In the event of a delay of several months, you may run the risk of being late for the administration of the second dose, when the effects on the immune system of the first dose have already disappeared or are excessively diminished. Other fears are linked to the possibility that millions of people will only be partially vaccinated, via the first dose, may increase the risk of developing new coronavirus mutations this can lead to the spread of new variants.

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