1. The author has either chosen not to mention recent references that have categorically shown poor effectiveness of aP vaccines vis-à-vis wP vaccines in head to head comparison [1-4] or only selectively used a particular reference without sharing key findings of the same [5,6]. For example, the paper by Sheridan SL, et al. [6] concludes: "In all scenarios, the reported rates of pertussis were significantly lower among children who had started the vaccination process with DTwP than among those who had started with DTaP" [6].

There may be several reasons for the upsurge of pertussis in all these countries as discussed by the authors, but the recent reports have analyzed subset of population and concluded that those who had received wP vaccines in the past were more protected than those who received all aP vaccines. These trials have concluded that not only faster waning, but aP vaccines were found to be wanted even for priming [1-6]. Hence, aP vaccines underperformed on both the fronts, i.e. primary induction and durability of immune responses. Studies conducted in US and Australia after the recent outbreaks have now conclusively proved that the change from wP to aP vaccines contributed to the increase in pertussis cases.

2. The author did not mention that when wP and aP were compared head to head, at least five studies showed that DTwP vaccines have greater efficacy than DTaP vaccines [7]. Still, the author tries to defend aP vaccines as "soft target." The perception that both the vaccines are of equal efficacy is based on older data and concepts.

3. The only advantage where aP vaccines score over wP is "reactogenicity". There is no difference between aP and the wP vaccines for rare severe events. Post-2012 outbreaks of pertussis in US, UK, and Australia have shifted the focus back on effectiveness of the pertussis vaccines from the safety. The
Advisory Committee on Immunization Practices (ACIP) and many US experts on pertussis have also discussed the option of going back to wP vaccines. But the problem with them and with the entire western world is that they cannot now revert to wP vaccines owing to "poor public acceptance" of these products. Fortunately, this is not a big issue as yet in India. There is no report of poor acceptance or widespread rejection of wP vaccines both from the public or private sector.

4. Coming to "the Indian perspective", the author has tried to justify the equal emphasis accorded to aP vaccines (versus wP vaccines) despite any evidence in favor of the former. India is essentially a wP vaccine using country and more than 95% of children are still vaccinated with wP vaccines. There is no data on the efficacy/effectiveness of aP vaccines in India and almost all the recommendations are based on the performance of these vaccines in industrialized countries, mainly USA. The aP vaccines are licensed in India based merely on immunogenicity data. In the absence of any known reliable and consistent ‘correlate of protection’ of either pertussis disease or vaccines, the immunogenicity data become redundant and cannot be relied as a sole proxy of protection. On the contrary, we have strong evidence of effectiveness, real life performance of wP vaccines from India where the widespread use of them have markedly reduced the incidence of pertussis. The incidence of pertussis declined sharply after launch of Universal Immunization Program (UIP). We have achieved a good control of pertussis (high effectiveness, not merely the efficacy) with whatever type of wP was available in the country despite with a modest coverage of around 60-70%. On the other hand, the epidemiology of pertussis and performance of wP and aP vaccines in US clearly shows that early use of wP vaccines had almost eliminated pertussis which has now resurged after use of even the highest quality aP vaccines with a very high coverage (close to 100%) since mid-1990s.

5. In the end, the author has shown a fear that affluent section of society may be deprived of "a low reactogenicity vaccine". On the contrary, by not offering them a higher efficacy vaccine, they are indeed deprived a chance to prime their kids with a superior product since even a single dose of wP vaccine offer significant resistance to future susceptibility to wild pertusisis as proved by recent studies [3,6]. Further, not 100% of kids are going to experience untoward reactions with the first dose of wP vaccine.