key: cord-0785678-j8s63vee
authors: Hills, T.; Hatter, L.; Kearns, N.; Bruce, P.; Beasley, R.
title: COVID-19 border controls prevent a 2021 seasonal influenza epidemic in New Zealand
date: 2021-09-20
journal: Public Health
DOI: 10.1016/j.puhe.2021.09.013
sha: e8765bff3a7814df1713779d6da5b3d984ab4cc7
doc_id: 785678
cord_uid: j8s63vee

nan

Letter to the Editor COVID-19 border controls prevent a 2021 seasonal influenza epidemic in New Zealand

The lack of seasonal influenza epidemics has been an unexpected feature of the COVID-19 pandemic, illustrated by WHO sentinel surveillance data from temperate Southern Hemisphere countries demonstrating a near absence of influenza since early 2020. 1 These observational data were consistent with the hypothesis that non-pharmaceutical interventions (NPIs) introduced to control the spread of COVID-19 could have dramatically reduced the burden of influenza and prevented seasonal epidemics. However, this finding did not shed light on the relative contribution of specific NPIs (such as widespread face mask use, school and workplace closures, physical distancing, travel restrictions, limits on gathering sizes, and border control measures) on reducing influenza activity, if the association was indeed causative.

The 2021 influenza surveillance data in New Zealand (NZ) informs this issue. 2 Up to week 32, 2021, there have been no positive influenza isolates reported to the WHO Global Influenza Surveillance and Response System, during which period an autumn/ winter epidemic would usually occur (Fig. 1) . From June 2020 until the recent outbreak in August 2021, NZ has predominantly been at 'alert level one' (https://covid19.govt.nz/alert-levels-and-updates/ history-of-the-covid-19-alert-system/), where NPIs are essentially limited to border controls and mandatory mask-wearing in specific situations (such as on public transport), with transient increases in alert levels to manage localised COVID-19 cases. Thus, the primary preventative measure is the ongoing closure of NZ's borders to almost all travellers, with the requirement for those entering NZ to isolate for 14 days in a designated Managed Isolation and Quarantine facility, except for travellers coming through the recently established (and transiently open) quarantine-free 'travel bubble' with Australia. These border controls are likely to have completely 

Public Health j o u r n a l h o me p a g e : w w w . e l s e v i e r . c o m/ l o ca t e / p u h e prevented the introduction of new influenza strains to NZ. New Zealanders, as part of a 'team of five million', have largely accepted the necessity of this measure to help protect our communities and most vulnerable against COVID-19. 3 To date, the influenza experience during COVID-19 in NZ contrasts with the historical view that mandatory travel restrictions are 'likely to be ineffective, infeasible, or unacceptable to the public', in a serious influenza pandemic, and the World Health Organisation recommendation that NPIs for influenza are not focused at international borders. 4, 5 Instead, NZ's experience suggests these interventions may be effective tools in specific contexts, such as island nations pursuing an elimination strategy. Border closure with managed quarantine measures may substantially reduce the risk in the setting of a global influenza pandemic, and the utility of such approaches in pandemic preparedness strategies should be re-evaluated. 

WHO -National influenza centres of the global influenza surveillance and Response System

Department of the Prime Minister and Cabinet. Sentiment and behaviours benchmark

Non-pharmaceutical public health interventions for pandemic influenza: an evaluation of the evidence base

Nonpharmaceutical interventions for pandemic influenza, international measures

Prof. Beasley and Dr. Hills have received funding from the Health Research Council of New Zealand outside the submitted work. There are no conflicts of interest.