COVID – 19 vaccines are biological products which have been developed to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2), the virus that causes coronavirus disease 2019 (COVID‑19).

Scientists around the world are developing many potential vaccines for COVID-19. These vaccines are all designed to teach the body’s immune system to safely recognize and block the virus that causes COVID-19.

Several different types of potential vaccines for COVID-19 are in development, including:

• Inactivated or weakened virus vaccines - which use a form of the virus that has been inactivated or weakened so it doesn’t cause disease, but still generates an immune response.
• Protein-based vaccines - which use harmless fragments of proteins or protein shells that mimic the COVID-19 virus to safely generate an immune response.
• Viral vector vaccines - which use a safe virus that cannot cause disease but serves as a platform to produce coronavirus proteins to generate an immune response.
• RNA and DNA vaccines - a cutting-edge approach that uses genetically engineered RNA or DNA to generate a protein that itself safely prompts an immune response.

There are 20 vaccines which have been authorized by at least one national regulatory authority for public use as follows:

• 2 RNA vaccines (Pfizer–BioNTech and Moderna)
• 9 conventional inactivated vaccines (BBIBP-CorV, Chinese Academy of Medical Sciences, CoronaVac, Covaxin, CoviVac, COVIran Barakat, Minhai-Kangtai, QazVac, and WIBP-CorV)
• 5 viral vector vaccines (Sputnik Light, Sputnik V, Oxford–AstraZeneca, Convidecia and Janssen)
• 4 protein subunit vaccines (Abdala, EpiVacCorona, MVC-COV1901, Soberana 02, and ZF2001)

In total, 330 vaccine candidates are in various stages of development, with 102 in clinical research, including 30 in Phase I trials, 30 in Phase I-II trials, 25 in Phase III trials and 8 in Phase IV development.

The WHO have so far listed 8 different types of vaccines for emergency use (EUL) as follows:

TMDA authorizes for marketing vaccines which have received prior recommendation from the Ministry of Health, Community Development, Gender, Elderly and Children. Vaccines which are currently allowed to be used in Tanzania include:

The emergency use listing (EUL) is a procedure introduced by WHO to assess the suitability of novel health products during public health emergencies. The objective is to make medicines, vaccines and diagnostics available as rapidly as possible to address the emergency, while adhering to stringent criteria of safety, efficacy and quality. The assessment weighs the threat posed by the emergency as well as the benefit that would accrue from the use of the product against any potential risks.

The EUL pathway involves a rigorous assessment of late phase II and phase III clinical trial data as well as substantial additional data on safety, efficacy, quality and a risk management plan with a focus on low- and middle-income country needs. These data are reviewed by independent experts and WHO teams who consider the current body of evidence on the vaccine under consideration, the plans for monitoring its use, and plans for further studies

As part of the EUL process, the company producing the vaccine must commit to continue to generate data to enable full licensure and WHO prequalification of the vaccine. The WHO prequalification process will assess additional clinical data generated from vaccine trials and deployment on a rolling basis to ensure the vaccine meets the necessary standards of quality, safety and efficacy for broader availability.

The COVID-19 vaccines produce protection against the disease, as a result of developing an immune response to the SARS-Cov-2 virus. Developing immunity through vaccination means there is a reduced risk of developing the illness and its consequences. This immunity helps you fight the virus if exposed. Getting vaccinated may also protect people around you, because if you are protected from getting infected and from disease, you are less likely to infect someone else. This is particularly important to protect people at increased risk for severe illness from COVID-19, such as healthcare providers, older or elderly adults, and people with other medical conditions.

Even if you have already had COVID-19, you should be vaccinated when it is offered to you. The protection that someone gains from having COVID-19 will vary from person to person, and we also don’t know how long natural immunity might last.

Is the percentage reduction of disease in a vaccinated group of people compared to an unvaccinated group, using the most favorable conditions. It is best measured using double-blind, randomized, controlled clinical trials. Vaccine effectiveness differs from vaccine efficacy in that vaccine effectiveness shows how well a vaccine works when they are always used and in a bigger population whereas vaccine efficacy shows how well a vaccine works in certain, often controlled, conditions. Vaccine efficacy studies are used to measure several possible outcomes such as disease attack rates, hospitalizations, medical visits and costs.

There were no any short cuts in developing these vaccines. All non-clinical and clinical studies were conducted to authentify the safety and efficacy of these vaccines. In general atleast three clinical studies are needed to be conducted in black populations with positive outcome before a vaccine could be allowed to be used in Tanzania. Data presented by manufacturers had proved that such studies were conducted. The TMDA also participated in the joint assessment of these vaccines through the African Vaccines Regulators Forum (AVAREF) which organized assessment workshops under the coordination of WHO.

From research findings accrued so far, only the Janssen vaccine is administered using a single dose while the rest needs two doses of 21 or 28 days apart depending on the type of vaccine. Manufacturers are still investigating if there is any waning effect by measuring immunogenicity and long term protective efficacy. Once studies are conclusive, dose regimens and adjustments will be shared.

Being vaccinated does not mean that we can throw caution to the wind and put ourselves and others at risk, particularly because research is still ongoing into how much vaccines protect not only against disease but also against infection and transmission. Vaccines developed so far are also not 100% protective against COVID-19.

There is no way a microchip or magnetic device could be attached to a vaccine. Vaccines are liquid formulations which can be clearly and visibly seen by a naked eye. There has recently been misinformation and myths that such devices could be attached to vaccines to impair fertility and reduce populations. These should be ignored and not shared to the wider community to promote vaccine use and increase coverage.

While COVID-19 vaccines have high levels of efficacy, especially against hospitalization and severe disease, no vaccine is 100% protective. As a result, there will be some small percentage of vaccinated people who fall ill with COVID-19 in spite of being vaccinated.

In addition to a vaccine's specific characteristics, several factors such as a person's age, their underlying health conditions, previous COVID-19 disease, current exposure to SARS-CoV-2, or the circulation of virus variants may have an impact on a vaccine’s effectiveness. We do not yet know how long immunity from different COVID-19 vaccines will last. That is one reason why, even as COVID-19 vaccines are being rolled out, we must continue using all public health measures that work to decrease exposure risk, such as physical distancing, masks and hand-washing.

For the first 14 days after getting vaccinated, you do not have significant levels of protection as the protection increases gradually. For a single dose vaccine, protection is generally considered to occur by two weeks after vaccination. For two-dose vaccines, both doses are needed to achieve the highest level of immunity possible.

While a COVID-19 vaccine is most effective against serious illness and death, TMDA is still learning about their ability to protect individuals from getting infected and passing the virus on to others. To help keep yourself and others safe, and while vaccination rolling out in your community, continue to maintain at least a one meter distance from others, cover a cough or sneeze in your elbow, clean your hands frequently and wear a mask, particularly in enclosed, crowded or poorly ventilated spaces. Always follow guidance issued by the Ministry of Health, Community Development, Gender, Elderly and Children.

Clinical trials in some countries are looking at whether you can have a first dose from one vaccine and a second dose from a different vaccine. There isn't enough data yet to recommend this type of combination.

More studies are needed to assess the effectiveness of the current COVID – 19 vaccines against the variants. A growing body of data suggests that most vaccines stimulate enough immunity to retain substantial efficacy against most variants, especially for severe disease, hospitalization and death. The impact of the variants on efficacy against mild disease and against infection without disease is more impacted than for the more severe outcomes.

The reason vaccines substantially retain protection against disease is likely related to the broad immune response they induce, which means that virus changes or mutations are unlikely to make vaccines completely ineffective. If any of these vaccines become less effective against one or more variants, it will likely be possible to change the composition of the vaccines to protect against these variants, however this will take time and additional data to fully evaluate. Data continues to be collected and analysed on new variants of the COVID-19 virus.

Safe and effective vaccines are a game-changing tool: but for the foreseeable future we must continue wearing masks, cleaning our hands, ensuring good ventilation indoors, physically distancing and avoiding crowds.

It’s not vaccines that will stop the pandemic, it’s vaccination. The Ministry through IVD is working tirelessly to ensure fair and equitable access to vaccines, and ensure everyone receives them and roll them out to protect Tanzanians starting with the most vulnerable. It should however be noted that getting a vaccine is not mandatory but rather optional to individuals who are ready to do so.

Because COVID - 19 vaccines have only been developed recently, it’s too early to know their duration of protection. Research is ongoing to answer this question. However, it’s encouraging that available data suggest that most people who recover from COVID-19 develop an immune response that provides at least some period of protection against re-infection – although scientists are still learning how strong this protection is, and how long it lasts.

Like any vaccine, COVID-19 vaccines can cause mild, short term side effects, such as a low-grade fever or pain or redness at the injection site. Most reactions to vaccines are mild and go away within a few days on their own. More serious or long-lasting side effects to vaccines are possible but extremely rare. TMDA continuously monitors safety of vaccines for as long as they are in use, to detect rare adverse events and implement approaches to limit their occurrence.

Reported side effects to COVID-19 vaccines have mostly been mild to moderate and short-lasting. They include: fever, fatigue, headache, muscle pain, chills, diarrhoea, and pain at the injection site. The chances of any of these side effects following vaccination differ according to the specific COVID-19 vaccine.

In most cases, these can be managed with rest, plenty of non-alcoholic liquids, and paracetamol or acetaminophen for the typical side effects. People should contact healthcare providers if the tenderness (pain) at injection site increases after 24 hours, or the side effects do not go away within a couple of days. In case of difficulty breathing, chest pain, confusion, loss of speech or mobility, a nearby health facility should be visited immediately.

The COVID-19 mRNA vaccine technology has been rigorously assessed for safety, and clinical trials have shown that mRNA vaccines produce an immune response that has high efficacy against disease. mRNA vaccine technology has been studied for several decades, including in the contexts of Zika, rabies, and influenza vaccines. mRNA vaccines are not live virus vaccines and do not interfere with human DNA.

The TMDA has two pharmacovigilance systems for safety surveillance of vaccines in the country. These are passive and active surveillance (cohort event monitoring - CEM) methodologies.

The passive system uses yellow forms (for healthcare providers) and green forms (for patients) to report adverse drug reactions (ADRs). The CEM method uses specially designed forms for active surveillance depending on the types of disease and medicine used. CEM method is used for newly introduced molecules including vaccines and targets mainly products used in wider circulation.

The TMDA will adopt the CEM method to monitor the safety of COVID – 19 vaccines to record all events including delayed ADRs.

Nonetheless, the passive system will simultaneously be used to continuously monitor the use of COVID-19 vaccines to identify and respond to any safety issues that might arise to assure they remain safe for use in Tanzania. The monitoring will be done in collaboration with the Immunization and Vaccines Development (IVD) programme which is under the Ministry of Health, Community Development, Gender, Elderly and Children.

As with any vaccine, TMDA closely monitors the safety and effectiveness of COVID-19 vaccines that are used in immunization programmes. If a health problem is reported following vaccination, a thorough investigation is usually conducted by TMDA in collaboration with IVD. In case of COVID-19 vaccines, CEM forms for safety data collection should be used. The forms are available at www.tmda.go.tz.

Nonetheless, it is rare to find that health problems occurring following receipt of a vaccine are actually caused by the vaccine itself. Health problems following vaccination are most often found to be coincidental and entirely unrelated to vaccination. Sometimes they are related to how the vaccine has been stored, transported or administered. Errors related to the delivery of the vaccine should be prevented by better training healthcare workers and strengthening the supply chain

In the very rare cases where a adverse reaction is suspected to be related to the vaccine itself, the vaccine will be suspended from use by TMDA while the situation is assessed. Further investigations will take place to determine what exactly caused the event and corrective measures will be put in place.

The COVID-19 vaccines are safe for most people 18 years and older, including those with pre-existing conditions of any kind, including auto-immune disorders. These conditions include: hypertension, diabetes, asthma, pulmonary, liver and kidney disease, as well as chronic infections that are stable and controlled.

However, care should be taken if you:

• Have a compromised immune system.
• Are pregnant or nursing your baby.
• Have a history of severe allergies, particularly to a vaccine (or any of the ingredients in the vaccine).
• Are severely frail.

Vaccination protects you from getting seriously ill and dying from COVID-19. For the first 14 days after getting a vaccination, you do not have significant levels of protection, then it increases gradually. For a single dose vaccine, immunity will generally occur two weeks after vaccination. For two-dose vaccines, both doses are needed to achieve the highest level of immunity possible.

While a COVID-19 vaccine will protect you from serious illness and death, we are still learning about the extent to which it keeps you from being infected and passing the virus on to others (transmission). The data that is emerging from countries is showing that the vaccines that are currently in use are protecting against severe disease and hospitalization. However, no vaccine is 100% effective and breakthrough infections are regrettable, but to be expected.

The current evidence shows that vaccines provide some protection from infection and transmission, but that protection is less than that for serious illness and death.

The Ministry and TMDA are still learning also about the variants of concern and whether the vaccines are as protective against these strains as the non-variant virus. For these reasons, and while many of those in the community may not yet be vaccinated, maintaining other prevention measures is important especially in communities where SARS CoV-2 circulation is significant. To help keep you and others safe, and while efforts continue to reduce viral transmission and ramp up vaccine coverage, you should continue to maintain at least a 1-metre distance from others, cover a cough or sneeze in your elbow, clean your hands frequently and wear a mask, particularly in enclosed, crowded or poorly ventilated spaces. Always follow guidance from the Ministry and IVD based on the situation and risk where you live.

The TMDA is mandated by the Tanzania Medicines and Medical Devices Act, Cap 219 to regulate both human and veterinary vaccines including COVID – 19 vaccines. Regulation covers registration of vaccines, import and export control, post-marketing surveillance, pharmacovigilance, inspection of the supply chain, licensing of premises, laboratory testing and clinical trials control.