Influenza and whooping cough (pertussis) vaccines in pregnancy

Until the Covid-19 pandemic, adult vaccinations were not considered a routine practice in India, with priority for vaccinations only to the children. The pandemic taught that vaccines are required across the life course. Young adults, adults and the elderly also need vaccines for better health, productivity and wellbeing.

However, when adults and elderly were taking Covid-19 vaccines in the middle of pandemic (early 2021), pregnant women were not allowed to take, citing potential risk of vaccine due to lack of safety data from Covid-19 vaccine trials, since pregnant women were denied access to participate in vaccine trials. We witnessed in-equality in access of essential vaccine in this high-risk group.

With the evidence of Delta (B.1.617.2) variant of SARS-CoV-2, (the virus that causes COVID-19), causing severe disease in pregnant women and endangering pregnancy, the Government of India in July 2021 approved and administered COVID-19 vaccines to all pregnant women as part of their standard antenatal care programme. Now, one hundred twenty countries recommend COVID-19 vaccination to pregnant women. This indicates that the severity and burden of the disease is critical to influence vaccine recommendations.

Unfortunately, vaccination of pregnant mothers has not been utilized to its full potential. The vaccines for influenza and pertussis (whooping cough) are available. These can be given during pregnancy. However, these are not still given under the national programme.

India has the largest burden of deaths in children under-5 years from lower respiratory infections. The major viral cause of lower respiratory infections in children is respiratory syncytial virus (RSV) and influenza and bacterial causes are streptococcus pneumoniae (pneumococcus) and Hemophilus influenzae type b (Hib). The pneumococcal and Hib vaccines are routinely given to Indian children. Seasonal influenza virus (flu or swine flu-H1N1), similar to Covid-19, is spread by the droplets produced from coughing and sneezing and produces symptoms of fever, cough, sore throat, runny nose, body aches, and headache. As compared to non-pregnant women, pregnant women with influenza are at a greater risk of developing severe illness and hospitalisation and adverse pregnancy outcomes in the developing baby.

Pertussis (whooping cough/KAALI KHANSI) caused by a bacteria bordetella pertussis, can cause severe illness and complications in children under three months of age, with initial symptoms of cold that progress to severe cough, struggle in breathing or breathing stops. Pertussis can even become deadly. Indian children get pertussis vaccines as part of the diphtheria “pertussis” tetanus (DPT) vaccine series starting at 1.5 months of age, but this immunity is not sufficient to protect during the first three months of life when their immune system is still developing and are at most risk. Pertussis immunity wanes down with age. So, when a woman enters pregnancy with a weak anti-pertussis immunity, her baby is not protected from the deadly disease during the early months of life.

Vaccination during pregnancy is a simple and effective tool to protect the mothers, developing baby, newborns and, young babies before they can get their own vaccines. Vaccine generated immunity (antibodies) gets transferred through placenta to the developing baby or via breastmilk to the babies during the most vulnerable months of life. Therefore, the mother’s risk of getting sick and of passing the disease to the babies gets reduced by vaccination.

Usually the toxoids (inactivated toxins) and inactivated vaccines are considered safe during pregnancy. Inactivated vaccine contains killed pathogen which does not produce disease when administered. These include tetanus toxoid, reduced diphtheria toxoid, acellular pertussis, inactivated influenza vaccine, Covid-19 vaccine (Covishield; recombinant viral vector), hepatitis B vaccine (protein).

Live vaccines such as influenza nasal spray vaccine, measles, mumps and rubella (MMR) vaccine, human papillomavirus vaccine, varicella (chicken pox) vaccine, yellow fever vaccine and Japanese encephalitis virus vaccine are not recommended during pregnancy.

In India, all pregnant women are administered two doses of tetanus toxoid (TT) or tetanus diphtheria (Td) as part of the government’s antenatal care (ANC) programme. With this, India successfully achieved the elimination of maternal and neonatal tetanus (MNT) – lockjaw in 2015, and, has significantly reduced the deaths of mothers and neonates (babies under 1 month), with which the yearly MNT is now <1 per 1,000 live birth.

The World Health Organization recommends pregnant women as the most priority group for influenza vaccination. Inactivated influenza vaccines (flu shot) can be given to pregnant women at any stage of pregnancy to protect from influenza viral strains that predominantly circulate in that year, for example swine flu-H1N1pdm, H3N2 and Influenza B for the year 2022. Children <6 months of age are not eligible to receive flu shots. Pregnant women are routinely administered flu vaccines in the US, UK, Australia and Canada. The Government of India recommended flu shots for pregnant women in 2016, but it has not yet been introduced in the national immunisation programme.

The Federation of Obstetric and Gynecological Societies of India (FOGSI) recommend reduced diphtheria toxoid, tetanus toxoid, and “acellular pertussis” (dTaP/Tdap) vaccination to pregnant women in second trimester (28-32 week) of pregnancy. However, the Government is yet to recommend that. Maternal Tdap vaccines are routinely given in the US, UK and Australia.

There is insufficient data on the burden of influenza in children and pregnant women in India which comes from the non-availability of routine diagnostics of influenza and pertussis in the government health systems. Cost is a concern, but given the severe complications flu can cause in pregnant women and children, vaccination can prevent these complications and health care expenses.

Influenza vaccine is available in private sector at a cost of INR 1200-2000, which is beyond the reach for economically weaker sections. The rate of maternal vaccination against influenza has been extremely poor, with published reports from Kashmir and Maharashtra. A part of this is due to poor knowledge and sensitisation among the obstetrician-gynaecologists in India about the severity of influenza and the need for vaccines. Awareness is also very low among public. Even coverage is very low among health workers. There is a misconception that flu is just a “cold” and vaccines are not needed or needed only during outbreaks. Maharashtra introduced maternal influenza vaccine in their immunization program in 2015, however, the uptake was poor, largely driven by the outbreaks. Further, the availability of vaccine is a deterrent since vaccines are modified every year and then imported during April-May for the flu season. Similarly, the uptake of Tdap is negligible in pregnant women and Indian adults.

The idea of maternal immunisation brings concern about vaccine safety. Therefore, the obstetrician gynaecologists, paediatricians, general physicians and health workers must be periodically informed, educated and counselled about the risk and severity of disease in infants and pregnant women, the need for vaccines and vaccine safety to dispel misinformation and develop vaccine confidence for supporting national recommendations. Pregnant women should also enquire about vaccines with their gynaecologists during routine check-ups.

Seasonal influenza and pertussis vaccines must be included in the national immunisation programme for pregnant women and given as part of the ANC to improve the pregnancy outcomes and reduce the burden of lower respiratory infections in children. Health systems need strengthening for disease diagnosis to build the evidence for arriving at recommendations for maternal vaccines.

The article has been authored by Tila Khan, MVSc, PhD (Virology), and Dipanwita Sengupta, PhD, Lancet Citizens’ Commission Fellows.