receive Tdap in place of their next Td booster (recommended to be given every ten years). Tdap and Td can be used as prophylaxis for tetanus in wound management. People who will be in contact with young infants are encouraged to get Tdap even if it has been less than five years since Td or TT to reduce the risk of infants being exposed to pertussis. NACI suggests intervals shorter than five years can be used for catch-up programs and other instances where programmatic concerns make five-year intervals difficult. The World Health Organization (WHO) recommends a pentavalent vaccine, combining the DTP vaccine with vaccines against Haemophilus influenzae type B and hepatitis B. Evidence on how effective this pentavalent vaccine is compared to the individual vaccines has not yet been determined. A 2019 study in the American Economic Journal found that state requirements mandating the use of the Tdap vaccine "increased Tdap vaccine take-up and reduced pertussis (whooping cough) incidence by about 32 percent." Related combination vaccines Excluding pertussis DT and Td vaccines lack the pertussis component. The Td vaccine is administered to children over the age of seven as well as to adults. It is most commonly administered as a booster shot every 10 years. The Td booster shot may also be administered as protection from a severe burn or dirty wound. The DT vaccine is given to children under the age of seven, who are unable to receive the pertussis antigen in the DTaP vaccine due to a contraindication. Including polio In the United States, a combined vaccine inactivated polio vaccine (IPV), DTaP, and hepatitis B vaccine is available for children. In the UK, all babies born on or after 1 August 2017 are offered a hexavalent vaccine: DTaP, IPV, Haemophilus influenzae, and hepatitis B. Contraindications The DPT vaccine should be avoided in persons who experienced a severe allergic reaction, such as anaphylaxis, to a past vaccine containing tetanus, diphtheria, or pertussis. It should also be avoided in persons with a known severe allergy to an ingredient in the vaccine. If the reaction was caused by tetanus toxoids, the CDC recommends considering a passive immunization with tetanus immune globulin (TIG) if a person has a large or unclean wound. The DPT vaccine should also be avoided if a person developed encephalopathy (seizures, coma, declined consciousness) within seven days of receiving any pertussis-containing vaccine and the encephalopathy cannot be traced