Frequently Asked Questions on Pertussis (Whooping cough) Vaccination in Pregnancy
- What is Pertussis?
Pertussis (also known as whooping cough) is caused by the bacterium named Bordetella pertussis. It is a highly contagious respiratory disease presenting with repeated bouts of coughing that may last for 2 to 3 months or even longer. The "whooping" noise is a loud high-pitched sound caused by gasping for breath after a bout of coughing, though not every patient has this.
- Who are at risk for pertussis? Which age group is most vulnerable to pertussis?
People of any ages can be infected with pertussis. Young infants are at the greatest risk of serious complications and mortality following infection. In 2017-2018, about 40% of the pertussis cases reported to the Centre for Health Protection were infants aged below six months who had not completed the primary series of pertussis vaccination.
- How serious can pertussis be?
Pertussis can cause pneumonia, apnea, respiratory failure, seizures, brain damage, and even death.
- How are babies infected with pertussis?
Babies usually contract pertussis via direct contact with or droplet transmission from their infected caregivers who may initially have non-specific symptoms like runny nose, sneezing, low-grade fever and mild cough. Hence, they may not know they have pertussis and can end up spreading it to the babies who have close contact with them.
- Why are pregnant women advised to receive the pertussis vaccine?
In general, the morbidity and mortality of pertussis are highest in infants. In recent years, upsurge of pertussis cases has been observed in different countries despite high vaccination coverage. Similar situation has also been observed in Hong Kong with marked increases in the annual number of reported cases since 2017.
Infants do not begin their vaccination against pertussis until 2 months of age according to the Hong Kong Childhood Immunisation Programme (HKCIP).
The Scientific Committee on Vaccine Preventable Diseases (SCVPD) recommended that pregnant women should receive one dose of acellular pertussis-containing vaccine during each pregnancy as part and parcel of routine antenatal care regardless of previous vaccination or natural infection history against pertussis. The antibodies produced can be passed to the foetus before birth for direct protection against pertussis in the first few months when the infant has not yet completed his/her own vaccination.
- When should pregnant women have the pertussis vaccine?
According to SCVPD, the timing of vaccination is recommended to be anytime in the second or third trimester, preferably before 35 weeks of gestation. Of note, the vaccine should be given preferably at least 15 days before the end of pregnancy, so that enough time is allowed for antibodies to develop in pregnant women, and passage of enough antibodies to the foetus before delivery for optimal protection. The antenatal clinics of Hospital Authority and Maternal and Child Health Centres of Department of Health will provide pertussis vaccination for pregnant women from 26 to 34 week of pregnancy.
- Should pregnant women receive the pertussis vaccine if they miss the vaccination during pregnancy?
For women who have not received any pertussis-containing vaccine during pregnancy, they are recommended to receive one dose of acellular pertussis-containing vaccine as early as possible after delivery, preferably before discharge from hospital. This can help protect mother from infection during postpartum period, hence avoiding transmission to the newborn baby.
- Is the pertussis vaccine safe in pregnancy?
Scientific evidence has shown that pertussis vaccines are very safe for the pregnant women and their babies.
- Which pertussis vaccine and how many doses of vaccine will pregnant women be given?
Pregnant women are recommended to receive one dose of diphtheria (reduced dose), tetanus & acellular pertussis (reduced dose) (dTap) vaccine during every pregnancy regardless of previous vaccination or natural infection history against pertussis. Diphtheria (reduced dose), tetanus, acellular pertussis (reduced dose) & inactivated poliovirus (dTap-IPV) vaccine can also be used.
- What are the side effects of the pertussis vaccine?
Side effects include swelling, redness or tenderness of the injection site. These are mild and only last a few days. Serious side effects are extremely rare.
- Will the pertussis vaccine in pregnancy cause pertussis?
No. The acellular pertussis vaccine is not a "live" vaccine. This means it doesn't contain active bacteria, and cannot cause pertussis to mother and her baby.
- Is it safe to breastfeed after getting the pertussis vaccine?
Yes, it is safe. Moreover, mothers can pass some pertussis antibody to their babies by breastfeeding.
- Will the baby still need to be vaccinated at two months if his/ her mother had the vaccine while pregnant?
Yes. The antibodies passed to the baby from mother will wane gradually when he/ she grows. As a result, the baby will still need to be vaccinated according to the HKCIP when they reach two months old. (For more information on HKCIP, please visit here)
- If a pregnant woman was vaccinated against pertussis in a previous pregnancy, does she need to be vaccinated again?
Yes. The vaccine-induced antibodies wane with time, so pregnant women should get re-vaccinated in each pregnancy to maximise protection for their babies by passing enough antibodies to their babies.
- If a pregnant woman was vaccinated against pertussis as a child, does she still need to get vaccinated again?
Yes. The vaccine-induced antibodies wane with time, so the vaccine is recommended in each pregnancy in order to allow the baby to get the greatest amount of antibodies from his/her mother to prevent infection.
- Do pregnant women still need pertussis vaccines if they have had pertussis before?
Yes. Similar to previous vaccination, past infection does not provide lifelong protection and immunity wanes with time. Therefore, pregnant women still need pertussis vaccines during every pregnancy.
- Does previous vaccination or infection result in lifelong protection against pertussis?
No. Previous vaccination or infection does not provide lifelong protection against pertussis, The immunity wanes with time.
- Who should not receive pertussis vaccine?
Pertussis vaccine is contraindicated for individuals who
- Had a severe allergic reaction to any vaccine component (including antibiotics or preservatives)
- Had a severe allergic reaction after a previous dose of pertussis-containing vaccine
- Developed encephalopathy (e.g., coma, decreased level of consciousness, prolonged seizures) not attributable to another identifiable cause within 7 days of administration of a previous dose of pertussis-containing vaccine
Note: The package inserts for individual products should always be referred to for the components and contraindications.
- Can pregnant women have the pertussis vaccine at the same time as the flu jab?
Yes. The two vaccines can be administered simultaneously or at any interval. Pregnant women can have the pertussis vaccine and the flu vaccine at the same time/ appointment, administered with a different syringe and at a different injection site, so do not delay the flu jab.
- Can pregnant women have the pertussis vaccine after receiving tetanus vaccine?
Yes. Pregnant women can safely get the pertussis vaccine (dTap) even if they recently got a tetanus (TT) or diphtheria toxoid-containing (Td) vaccine. dTap can be given regardless of the interval since the last TT or Td was given.