Pertussis (whooping cough) is a highly contagious acute respiratory tract infection caused by Bordetella pertussis — characterised by paroxysmal coughing fits followed by a high-pitched inspiratory "whoop." It causes approximately 24 million cases and 160,000 deaths per year globally, predominantly in infants who are too young to be fully vaccinated. Despite high vaccine coverage in many countries, pertussis remains endemic globally and resurges every 3-5 years.

Why is pertussis still so common despite vaccination?

Three key reasons: (1) Waning immunity — immunity from acellular pertussis (aP) vaccines, widely used in high-income countries, wanes significantly within 4-7 years, creating a pool of susceptible adolescents and adults. (2) Suboptimal vaccine coverage — globally, many children do not complete the infant primary series. (3) Biological: B. pertussis strains evolve to partially escape vaccine-induced immunity. Whole-cell pertussis vaccines (used in LMICs) produce longer-lasting but more reactogenic immunity.

Infants under 3 months: highest risk of death — too young to have received full protection from their own vaccination. Adolescents: waning aP immunity makes them susceptible; often have atypical presentations (persistent cough without "whoop") and unknowingly transmit to infants. Adults — particularly parents, grandparents and healthcare workers — are the most common source of infant infection. Healthcare workers who are sources of infant pertussis are particularly concerning.

What is maternal vaccination and why is it so effective?

Administering Tdap vaccine to pregnant women (ideally at 27-36 weeks of each pregnancy) generates maternal antibodies that are actively transferred to the fetus in late pregnancy — protecting newborns from birth, before they can be vaccinated. This provides 91% protection against infant hospitalisation and 95% against death. Maternal Tdap is now recommended by WHO, the US (CDC), UK, Australia and many other countries. It is the most impactful intervention against infant pertussis deaths currently available.

What are the stages of pertussis?

Pertussis has three classic stages: (1) Catarrhal stage (1-2 weeks): mild cold-like symptoms — runny nose, mild cough, low-grade fever. Highly infectious but not yet recognisable as pertussis. (2) Paroxysmal stage (2-10 weeks): severe paroxysmal coughing fits with whoop; post-tussive vomiting; apnoea in infants; facial cyanosis. Most recognisable stage. (3) Convalescent stage (weeks to months): gradual recovery, decreasing cough severity. Relapses with subsequent respiratory infections are common.

How is pertussis treated?

Macrolide antibiotics: azithromycin (first choice — 5 days), clarithromycin or erythromycin (if started in the catarrhal phase, shortens illness duration and infectivity period significantly). If started in the paroxysmal phase, antibiotics reduce infectivity but do not shorten duration of cough. Post-exposure prophylaxis: azithromycin for close household contacts (especially households with infants under 12 months). Supportive care for severe infant pertussis: ICU, mechanical ventilation for apnoea, IV fluid support.

Can adults get pertussis?

Yes — adults are a significant reservoir. Waning immunity from childhood aP vaccination allows adults to develop pertussis, often with atypical presentation: prolonged cough (>3 weeks) without classic whoop. Adults frequently don't recognise their illness as pertussis and delay seeking care. They are the primary source of infant exposure. Adolescent and adult Tdap boosters reduce transmission to infants, though effectiveness of the cocoon strategy is lower than maternal vaccination.

What is the difference between DTP and Tdap vaccines?

DTP (diphtheria, tetanus, pertussis): full-strength primary infant series. DTaP uses acellular pertussis antigen (used in HICs). DTP or DTPw uses whole-cell pertussis (used in LMICs — longer-lasting immunity). Tdap: reduced-antigen booster formulation for adolescents and adults — contains the same antigens as DTaP but at lower doses to reduce reactogenicity. Tdap is used for: adolescent booster (single lifetime dose); adult booster; and maternal vaccination in each pregnancy.

Is there a risk of pertussis in Georgia?

Georgia has achieved high DTP coverage — but pertussis circulates in cyclical epidemics throughout the Caucasus region. Maternal Tdap is increasingly available. PHIG monitors pertussis surveillance and recommends healthcare worker Tdap vaccination. The Georgian Medical Journal covers pertussis epidemiology in the South Caucasus.

How does GMJ News cover pertussis?

GMJ News covers WHO pertussis burden data, maternal Tdap vaccination evidence, resurgence epidemiology, treatment guidelines and Georgia's immunisation programme. Pertussis is directly relevant to PHIG's maternal immunisation agenda and the Georgian Medical Journal's infectious disease coverage.

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Pertussis (Whooping Cough)

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Pertussis (whooping cough) — caused by Bordetella pertussis — infects an estimated 24 million people and kills 160,000 per year globally, predominantly infants under 3 months too young to be fully vaccinated (WHO). Despite near-universal infant vaccination, pertussis is paradoxically resurging in many high-income countries — because immunity from DTP vaccines wanes within 4-7 years. Maternal vaccination with Tdap during pregnancy (providing passive antibody protection to newborns before they can be vaccinated) is the most impactful strategy for preventing infant pertussis deaths and is now recommended by WHO.

Key messages

24 million cases — resurgence

Pertussis (whooping cough) causes approximately 24 million cases and 160,000 deaths per year globally — and is paradoxically resurging in countries with high DTP vaccine coverage due to waning immunity from both vaccination and natural infection (WHO 2023).

Infant deaths

Pertussis deaths are almost exclusively in infants under 3 months — too young to be fully vaccinated. Most infant pertussis is acquired from parents, siblings or other close contacts who are themselves infected but may only have a mild cough.

Maternal Tdap vaccination

Maternal vaccination with Tdap (combined tetanus, diphtheria, acellular pertussis) during pregnancy (ideally 27-36 weeks) provides passive antibody protection to newborns before they can be vaccinated — reducing infant pertussis hospitalisation by 91% and deaths by 95%.

Waning immunity

Immunity from acellular pertussis (aP) vaccines wanes within 4-7 years — shorter than from whole-cell pertussis (wP) vaccines used in LMICs and from natural infection. This waning immunity in adolescents and adults creates a reservoir for transmission to vulnerable infants.

SAGE recommendations

WHO's Strategic Advisory Group of Experts (SAGE) recommends: maternal Tdap in pregnancy; infant primary series at 6, 10, 14 weeks; booster at 15-18 months; adolescent booster; and healthcare worker vaccination.

Azithromycin treatment

Azithromycin (or clarithromycin) reduces duration and infectivity of pertussis if started in the first 3 weeks. Post-exposure prophylaxis for close contacts of cases (particularly in households with infants) is recommended.

Key statistics

24M

estimated pertussis cases/year

WHO

160K

estimated pertussis deaths/year

WHO

<3mth

age of virtually all pertussis deaths

WHO/CDC

91%

reduction in infant hospitalisation with maternal Tdap

Cochrane/WHO

4-7yr

duration of aP vaccine immunity (waning)

WHO/research

86%

global DTP3 coverage (2023)

WHO/UNICEF

Reported pertussis cases globally per year 2000-2023 — WHO

Source: WHO official reported cases (massively underestimated). Cyclical epidemics every 3-5 years; resurgence in high-income countries.

Glossary of key terms

Bordetella pertussis
WHOA fastidious Gram-negative coccobacillus — the causative agent of pertussis. Highly contagious (attack rate >80% in susceptible contacts). Produces pertussis toxin, adenylate cyclase toxin and other virulence factors causing the characteristic cough.

Paroxysmal cough
WHO/ClinicalThe hallmark of pertussis — violent, repeated coughs in rapid succession until air is exhausted, followed by a sudden inspiration ("whoop"). The whoop may be absent in infants (who may instead have apnoea), adults and partially immune individuals.

Acellular pertussis vaccine (aP)
WHO/SAGEA purified component pertussis vaccine containing 2-5 antigens (pertussis toxoid, filamentous haemagglutinin, pertactin, fimbriae). Less reactogenic than whole-cell pertussis (wP) but produces shorter-lasting immunity (4-7 years vs 10-15 years for wP).

Tdap vaccine
WHOA reduced-antigen formulation of tetanus, diphtheria and acellular pertussis vaccine — used for booster doses in adolescents and adults (including pregnant women). The maternal Tdap dose during pregnancy is the most effective intervention against infant pertussis deaths.

Cocoon strategy
CDC/WHOVaccination of all close contacts (parents, siblings, grandparents, caregivers) of newborns with Tdap to reduce infant exposure — the "cocoon." Less effective than maternal vaccination because it is harder to implement; maternal vaccination provides more reliable newborn protection.

Apnoea in infants
WHO/AAPYoung infants with pertussis may not produce the characteristic "whoop" — instead presenting with apnoea (breathing pauses), cyanosis and feeding difficulties. Pertussis should be considered in any infant with unexplained apnoea — it is rapidly fatal in very young infants.