What is the Tdap vaccine?
The TDAP vaccine is a combination vaccine providing protection against three diseases: tetanus, diphtheria, and pertussis (whooping cough) [1]. It is a vaccine that is made by inactivating a pathogen by heat or radiation, meaning that it does not contain live pathogen and cannot give you the disease it protects against [1].
Which diseases does the TDAP vaccine protect against?
The TDAP vaccine protects against:
- Tetanus (lockjaw) - a bacterial infection that causes muscle tightening, eventually leading to difficulty breathing and sometimes death [1].
- Diptheria - a bacterial infection that affects the respiratory system which can lead to difficulty breathing and heart failure [1].
- Pertussis (whooping cough) - a respiratory disease that causes uncontrollable, violent coughing to the extent that broken ribs have been reported as a consequence of the cough [1].
Who should get the TDAP vaccine?
The TDAP vaccine is indicated for children 7 years of age and older, adolescents, and adults:
- Adolescents should receive a single dose of TDAP, preferably at age 11 or 12 years.
- Pregnant women should get a dose of TDAP during every pregnancy, preferably early in the third trimester to protect the child from pertussis.
- Adults who have not received TDAP yet should do so as soon as possible.
- Adults who received TDAP should get a booster dose of TDAP (or a specific booster vaccine Td) every 10 years, or after 5 years in case of a severe dirty wound or burn [2].
How effective is the TDAP vaccine?
The TDAP vaccine is very effective at reducing the incidence of tetanus, diphtheria and pertussis. Since being introduced to public health systems, the rates of tetanus and diphtheria have dropped by 99 percent, and the rates of pertussis dropped by 80 percent [3]. The incidence of pertussis is projected to further drop with a more widespread use of the TDAP vaccines in healthcare workers and adolescents in the United States [4].
Side effects of vaccines: What are they and why do they occur?
Vaccination is arguably the most important public health intervention. Vaccines protect us from various infectious diseases, and it is important that they are continuously used in public health.
However, vaccines sometimes cause side effects. This happens with every therapeutic. In the case of vaccines, the side effects usually stem from the body's immune system reacting to the antigen and building immunity against the pathogen the vaccine protects against.
In essence, a vaccine is like a blueprint of the pathogen, providing a 'practice target' for the immune system. Therefore, the side effects may resemble a mild illness; the most common of which are:
- pain and swelling at the injection site,
- mild fever,
- fatigue [5].
These usually resolve within a few days.
In a study conducted in Spain, out of 13,837 people, 45.20% reported these mild symptoms, 24.89% reported moderate symptoms. Approximately 15% reported side effects as 'severe', however these mostly constituted extreme tiredness and nausea / vomiting, not life threatening conditions [6].
In another study conducted in Pakistan, the most common side effects reported were fever (33.2%), pain at the injection site (35.9%), and fatigue (23.1%) [7].
The side effects can be influenced by multiple factors:
- Type of vaccine - mRNA vaccines tend to be associated with more severe adverse effects [7],
- Composition of the vaccine - some additives can cause reactions [8],
- Patient's gender and age - younger individuals and women tend to experience more severe adverse effects [7].
Side effects of the TDAP vaccine
The TDAP vaccine is generally regarded as very safe and well tolerated. Most side effects are usually mild and resolve within a few days.
The most common side effect is pain at the injection site, occurring in 2 out of 3 patients [9]. Other common side effects include redness, tenderness, and swelling at the injection site, body aches, headache, fatigue, nausea, vomiting, diarrhea, mild fever, and chills [1, 10, 11, 12].
In rare cases, the vaccine may cause allergic reactions or other more serious side effects. These usually present with severe swelling, pain or bleeding at the injection site, a very high fever, and signs of an allergic reaction such as hives, swelling of the face or throat, difficulty breathing, rapid heart rate, and dizziness [1]. If you believe you are experiencing these symptoms following a TDAP vaccination, seek medical care immediately.
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Severe adverse effects (though rarely reported) usually occur within a few minutes to a few hours following the vaccination [1]. This is the reason patients are often asked to wait for approximately 15 minutes after being vaccinated.