[2] Petousis-Harris was a Senior Lecturer at the Department of General Practice and Primary Health Care, University of Auckland from 2012 until February 2020 when she attained the position of associate professor.
[15] Prior to the conference, Petousis-Harris had drawn attention to the risks of children suffering permanent hearing loss if ear infections were not dealt with promptly by vaccination.
[16] Petousis-Harris earlier said the study demonstrated that the vaccine Synflorix reduced pneumonia, middle ear infections and hospitalisation from invasive pneumococcal disease (IPD).
[18] A paper co-authored in 2019 by Petousis-Harris, however, claimed: that in spite of vaccination having reduced mortality rates...an estimated 16 million pertussis cases and 195,000 child deaths [occurred globally] every year, with the greatest burden in low and middle-income countries.
"[22] The impact on infants of Tdap vaccine in utero was evaluated in a 2019 study in which Petousis-Harris participated and the findings [supported] "the safety of administration of pertussis immunisation during pregnancy".
Petousis-Harris and Hannah Chisholm, an epidemiologist from Auckland University,[25] explained how the usual cycles of herd immunity had been disrupted by COVID-19 restrictions, and with declining immunisation coverage, whooping cough along with measles, respiratory syncytial virus and influenza was likely to increase.
It was also noted that other social and environmental factors that contributed to the spread of infectious such as housing conditions, needed to be dealt with by interventions and policies but this was a challenge because of an "under-resourced workforce, and a revised health system that [had] yet to demonstrate its worth".
[27] The article noted that the vaccine's excellent safety profile was reflected in the fact that it had protected up to 80% of New Zealanders under 20 years of age, and there appeared to be little benefit in continuing the programme.
Their research, therefore, was a retrospective case-control study of New Zealand patients at sexual health clinics aged 15–30 years who were diagnosed with gonorrhoea or chlamydia, or both and were born between 1 January 1984, and 31 December 1998 – making them eligible to receive MeNZB during the earlier pandemic.
[37] The research team responded, agreeing with some of the points raised about randomised controlled trials, but clarified that "their study [was] on vaccine effectiveness...normally assessed using observational methods such as case-control and cohort designs".
[39] She told Susan Scutti, in an interview on CNN, that "even moderate protection against the sexually transmitted disease could have significant impact because the bacteria that cause it are very tricky...[and]...develop resistance to drugs by transferring genes in atypical ways and recombining with related bacterial species".
[40] Early in her career, Petousis-Harris held concerns about the quality of immunization coverage in New Zealand and was involved in research programmes to identify primary care factors that impacted this.
[41] The paper cited surveys from Area Health Boards in New Zealand in the 1990s that found in general, 68–80% of caregivers felt they did not have enough information about vaccination, and between 2–8% did not feel immunization was important.
[42][43] In 1998, as part of a wider strategy to increase immunisation rates, the New Zealand Ministry of Health funded a national toll-free hotline, hosted at the University of Auckland.
Petousis-Harris was part of a team that analysed data collected on this line with a goal to compare the caller profiles and the nature of their inquiries over equal periods between 1999 and 2003.
The research paper, co-authored by Petousis-Harris and released in 2005, showed changes in caller profiles, including use of the line by a higher number of health professionals, many of whom referred patients directly to the service, or were informed enough to respond to parental questions.
It noted that socioeconomic deprivation in the practice population was a determinant in the effectiveness of immunization delivery and children living in households with poverty-related issues suffered more frequently from acute illness.
[52] Early in 2020, when most of the cases of COVID-19 were still in China, and before it was declared a pandemic by The World Health Association on 11 March,[53] Petousis-Harris published an opinion piece on the University of Auckland website which explained the background of the virus and indicated that the swift response of international authorities was a good sign a vaccine would be developed quickly.
[54] Interviewed on New Zealand television (5 March 2020), Petousis-Harris clarified that the virus was most likely spread by respiratory secretions such as saliva and mucus and people needed to be careful to wash their hands regularly, particularly at airports.
Also on 24 April 2020, she agreed with the Prime Minister, Jacinda Ardern, that New Zealand could eliminate COVID-19 because the country had shown "decisive action, with strong leadership and very clear communications to everybody".
[57] By May 2020, Petousis-Harris was giving information on the systems and organisations that would advise, measure, monitor and assess vaccine safety, and was confident that with good tools, the process had begun and no steps were being omitted, in spite of the risks.
[59] On 10 September 2020, when one of the companies developing a COVID-19 virus put a hold on its trials due to a participant experiencing a serious health event, Petousis-Harris clarified that this was no cause for concern as it was about ensuring levels of "rigour and standards...[that are]...applied to all vaccines – at least those receiving support from CEPI, or the Coalition for Epidemic Preparedness Innovation".
[67] When it looked likely that the Pfizer BioNtech and Janssen Biotech vaccines for COVID-19 would be rolled out in New Zealand in early December 2020, Petousis-Harris was one of a group of experts who discussed some of the risks associated with this.
[70] During the rollout of the COVID vaccine in New Zealand in 2021, when the group Voices for Freedom, co-founded by Claire Deeks, distributed pamphlets that contained misinformation about the response to the COVID-19 pandemic, Petousis-Harris joined other health professionals and scientists in debunking all of the claims in the documents.
[72] When providing expert advice for the preparation of an article in the Western Leader, Petousis-Harris stated that the trials for COVID vaccines had been "more stringent and transparent because the world [was] watching".
[75] In a ruling on 15 February 2022, with regard to mandated vaccinations for members of the police and defence forces, a New Zealand High Court judge stated [he was] "not satisfied that the Crown [had] put forward sufficient evidence to justify the measures that have been imposed, even giving it some benefit of the doubt".
In 2018 Petousis-Harris was awarded a five-year Dean's Fellowship by the Faculty of Medical and Health Sciences, University of Auckland, to research infectious diseases and the vaccines that help prevent them.