Virus World

A new vaccine for dengue received prequalification from the World Health Organization (WHO) on 10 May 2024. TAK-003 is the second dengue vaccine to be prequalified by WHO. Developed by Takeda, it is a live-attenuated vaccine containing weakened versions of the four serotypes of the virus that cause dengue. 

WHO recommends the use of TAK-003 in children aged 6–16 years in settings with high dengue burden and transmission intensity. The vaccine should be administered in a 2-dose schedule with a 3-month interval between doses.  “The prequalification of TAK-003 is an important step in the expansion of global access to dengue vaccines, as it is now eligible for procurement by UN agencies including UNICEF and PAHO,” said Dr Rogerio Gaspar, WHO Director for Regulation and Prequalification.  “With only two dengue vaccines to date prequalified, we look forward to more vaccine developers coming forward for assessment, so that we can ensure vaccines reach all communities who need it.” The WHO prequalification list also includes CYD-TDV vaccine against dengue developed by Sanofi Pasteur.  Dengue is a vector-borne disease transmitted by the bite of an infected mosquito. Severe dengue is a potentially lethal complication which can develop from dengue infections.  It is estimated that there are over 100-400 million cases of dengue worldwide each year and 3.8 billion people living in dengue endemic countries, most of which are in Asia, Africa, and the Americas. The largest number of dengue cases reported was in 2023 with the WHO Region of the Americas reporting 4.5 million cases and 2300 deaths. Dengue cases are likely to increase and expand geographically due to climate change and urbanization.

The move is meant to fast-track national vaccination drives.  The World Health Organization on Thursday listed the Pfizer/BioNTech COVID-19 vaccine for emergency use, making it the first to receive such status since the pandemic began. The WHO Emergency Use Listing opens the door for countries to fast-track their own regulatory approval to import and administer the Pfizer/BioNTech vaccine.The objective of the procedure, the organization said, is to make medical products like vaccines available as rapidly as possible to address public health emergencies while adhering to stringent safety and quality checks.  The review of the Pfizer/BioNTech vaccine found that it met WHO criteria for safety and efficacy, and that the benefits of using the vaccine to address COVID-19 offset potential risks. The United Kingdom was the first Western country to authorize Pfizer/BioNTech's vaccine.

January 26, 2021 - The WHO Strategic Advisory Group of Experts (SAGE) on Immunization has issued Interim recommendations for use of the Moderna mRNA-1273 vaccine against COVID-19 in people aged 18 years and older. Here is what you need to know.Here is what you need to know.

Who should be vaccinated first?

As with all COVID-19 vaccines, health workers at high risk of exposure and older people should be prioritized for vaccination. As more vaccine becomes available, additional priority groups should be vaccinated, with attention to people disproportionately affected by COVID-19 or who face health inequities.

Who else can take the vaccine?

The vaccine is safe and effective in people with known medical conditions associated with increased risk of severe disease, such as hypertension, diabetes, asthma, pulmonary, liver or kidney disease, as well as chronic infections that are stable and controlled. Although further studies are required for immunocompromised persons, people in this category who are part of a group recommended for vaccination may be vaccinated after receiving information and counselling.
Persons living with HIV are at higher risk of severe COVID-19 disease. Known HIV-positive vaccine recipients should be provided with information and counselling. Vaccination can be offered to people who have had COVID-19 in the past. But individuals may wish to defer their own COVID-19 vaccination for up to six months from the time of SARS-CoV-2 infection. The vaccine can be offered to a breastfeeding woman who is part of a group recommended for vaccination (e.g. health workers); discontinuing breastfeeding after vaccination is currently not recommended.

Who should not take the vaccine?

While pregnancy puts women at a higher risk of severe COVID-19, the use of this vaccine in pregnant women is currently not recommended, unless they are at risk of high exposure (e.g. health workers). Individuals with a history of severe allergic reaction to any component of the vaccine should not take this or any other mRNA vaccine. While vaccination is recommended for older persons due to the high risk of severe COVID-19 and death, very frail older persons with an anticipated life expectancy of less than 3 months should be individually assessed. The vaccine should not be administered to persons younger than 18 years of age pending the results of further studies.

What’s the recommended dosage?

SAGE recommends the use of the Moderna mRNA-1273 vaccine at a schedule of two doses (100 µg, 0.5 ml each) 28 days apart. If necessary, the interval between the doses may be extended to 42 days. Compliance with the full schedule is recommended and the same product should be used for both doses.

Is it safe?

While this vaccine has yet to be approved by WHO for an Emergency Use Listing, it has undergone review by the European Medical Agency (EMA) and consequently meets WHO’s criteria for SAGE consideration. The EMA has thoroughly assessed the data on the quality, safety and efficacy of the Moderna COVID-19 vaccine and authorized its use across the European Union.
SAGE recommends that all vaccinees be observed for at least 15 minutes after vaccination. Those who experience an immediate severe allergic reaction to the first dose should not receive additional doses. Longer-term safety assessment involves continued follow up of clinical trial participants, as well as specific studies and continued surveillance of secondary effects or adverse events of those being vaccinated in the roll out. The Global Advisory Committee on Vaccine Safety, a group of experts that provides independent and authoritative guidance to the WHO on the topic of safe vaccine use, receives and assesses reports of suspected safety events of potentially international impact. 

How efficacious is the vaccine?

The Moderna vaccine has been shown to have an efficacy of approximately 92 per cent in protecting against COVID-19, starting 14 days after the first dose.

Does it work against new variants?

Based on the evidence so far, the new variants of SARS-CoV-2, including the B.1.1.7 and the 501Y.V2, do not alter the effectiveness of the Moderna mRNA vaccine. The monitoring, collection and analysis of data on new variants and their impact on the effectiveness of COVID-19 diagnostics, treatments and vaccines continues.

Does it prevent infection and transmission?

We do not know whether the vaccine will prevent infection and protect against onward transmission. Immunity persists for several months, but the full duration is not yet known. These important questions are being studied. In the meantime, we must maintain public health measures that work: masking, physical distancing, handwashing, respiratory and cough hygiene, avoiding crowds, and ensuring good ventilation.

The presentation summarizes the global efforts of W.H.O. to support the development, test, and manufacture of  COVID-19 vaccine in record times. The time for approval of a vaccine averages  10 years. However, the process is expected to be reduced by more than 5 times for COVID-19. This presentation, updated as of October 6, 2020,  summarizes the W.H.O. global efforts towards this goal, and also provides and excellent summary of the vaccine development process.

As of today, at least 213 COVID-19 vaccines are under development, including 178 preclinical candidates and 35 vaccines in human trials. Nine  vaccines have already entered advanced Phase III trials. With typical approval rates of 7% for preclinical candidates, and 20% for those entering human trials, more than 30 vaccines  against SARS-CoV-2 could be approved in the following years, and about two of them  in the following months.