The Government is rushing to plug any gaps in New Zealand’s defences against Omicron as cases start to rise precipitously, Marc Daalder reports
Analysis: A decision to shorten the gap between the second vaccine dose and the booster shot will help shore up one of New Zealand’s two front lines of defence against the rapidly-spreading Omicron variant.
More than half of District Health Boards have reported a case of Covid-19 in their rohe over the past few days and the Ministry of Health says Omicron now makes up most cases in the country.
A well-boosted population is critical to slowing the spread of the virus and protecting the health system, experts say.
Building up our immunity wall
“Data from the UK Health Security Agency indicates that for people three or more months after a second dose of the Pfizer vaccine, their protection against symptomatic infection is under 20 percent,” Te Pūnaha Matatini principal investigator and disease modeller Dion O’Neale said.
“This jumps to over 60 percent vaccine effectiveness against symptomatic infection after a booster dose. By reducing the interval between a second and a third dose, we are significantly increasing the proportion of the population who are currently able to get a booster and take advantage of that protection.”
Currently, just under 640,000 New Zealanders are eligible for a booster but haven’t yet had one. That number will swell to 1.78 million on Friday, when the three-month gap comes into effect.
The move comes alongside a surge in the booster rollout. Over the summer, less than 100,000 New Zealanders were getting boosted each week. The country’s collective immunity was actually declining each day, as far more people were experiencing waning immunity from their first two doses than were getting boosted. That pattern has flipped with the arrival of Omicron – around a quarter of a million New Zealanders have been boosted each week and New Zealand is building its “immunity wall” back up.
The effort to shore up New Zealand’s immunity wall against Omicron is particularly important given the lack of prior spread of Covid-19 in the country. The United Kingdom has vaccinated and boosted a slightly smaller proportion of its eligible population, but many more Brits have been infected over the past two years, lending them an extra layer of protection.
In early December, British experts predicted that prior infections would help bolster the country’s collective immunity against Omicron. Tim Spector, professor of genetic epidemiology at King’s College London, told the Financial Times that the UK had “paid the price” for large Covid-19 waves earlier in 2021 through illness and deaths.
Nonetheless, he said, "I’d much rather be in our position than a country that has had much lower levels of infection so far".
Mask progress lags
Little progress has been made on the other potential frontline defence mechanism: A surge in the use of effective P2 respirators (known overseas as N95s or KN95s). Health experts have said this intervention could be just as effective as vaccines.
"Masks are arguably more effective at stopping someone from transmitting Omicron than being double vaccinated with Pfizer vaccine. But there has not been the same emphasis," University of Otago epidemiologist Michael Baker told Newsroom in January.
Baker, alongside Jennifer Summers, Amanda Kvalsvig, Matire Harwood and Nick Wilson, called for a new mask strategy in a blog post two weeks ago. This would highlight the increased efficacy of P2 respirators in poorly-ventilated indoor spaces and would ensure that such masks were available cheaply or freely to all New Zealanders.
This would be "a highly cost-effective and equitable approach that could have significant benefits in an Omicron outbreak," Kvalsvig told Newsroom.
The Government has required that workers subject to a vaccine mandate (about 40 percent of the workforce) wear surgical masks or N95 respirators. Director-General of Health Ashley Bloomfield disputed independent health experts' arguments that respirators are far more effective than surgical masks, saying they need to be fit-tested for that to be the case.
But that conflicts with his department's advice to Covid-19 Response Minister Chris Hipkins in a June 2021 briefing about mask use by the MIQ workforce and by returnees in MIQ. In that briefing, Ministry of Health deputy chief executive Sue Gordon wrote that fit-testing boosted the efficacy of respirators but "even non-fit tested P2/N95 particulate respirators are likely to offer a greater level of respiratory protection than the ear loop medical masks currently in use".
What's clear is that the Government doesn't have the stock on hand to distribute respirators to every New Zealander. Only about 25 million respirators are stored in the Ministry of Health's Central Supply of PPE, a spokesperson told Newsroom. While respirators can be reused, it is recommended they are rotated on a daily basis and used only once a week.
Testing boosted ahead of peak in demand
One other key move the Government has made in preparation for Omicron is to order a vast quantity of rapid antigen tests (RATs). More than 50 million test kits are now expected to arrive in the country by the end of March and modelling predicts as many as nine million will be needed each week at the peak of the outbreak solely to clear infected people to return to work.
The Government got off to a late start on ordering these tests. In September, its real-time advisory group, led by Sir Brian Roche, recommended a massive expansion in the use of rapid tests as New Zealand prepared to reconnect to the world.
"It is critical that we actively promote and achieve widespread testing across the community irrespective of the known presence of the virus in the community. The availability of rapid antigen testing is critical to that and will form a key element of the surveillance strategy that needs to be adopted as part of Reconnecting New Zealanders," Roche wrote.
"The ability to detect and respond immediately will be a key element of success. It is our view that rapid antigen testing is introduced for areas that have vulnerable groups, before entry into hospitals, aged residential care facilities, prisons, forensic facilities, and so forth."
That warning came two days after a previously-unreported letter from laboratory experts on the Government's Science and Technology Advisory Group saying rapid testing would be needed when New Zealand transitioned to "endemicity" - or at least a state where the virus was prevalent in the community but could be prevented from threatening the health system.
"We anticipate RATs will be needed to combat staff shortages, both in healthcare and the wider workforce by testing before coming to work to avoid stand-down amongst other workers," microbiologist Gary McAuliffe wrote in the letter.
"Implementation planning for implementing RATs is required for intended use scenarios including frequent testing in healthcare workers, schools, work places, mass events. These require piloting now as time is not on our side."
However, a Ministry of Health spokesperson said the first orders for RATs had only been placed in October and those were for smaller quantities of tests. The number of tests ordered only "increased substantially" in "early December".
Efforts at the border to delay Omicron's arrival in time for boosters to be administered and more tests to be secured may have been crucial in allowing New Zealand to avoid an overwhelmed health system. But with the virus now spreading in the community, we no longer have room for error or delay in the next phase of the response.
The precautionary approach embraced by the Government in March 2020 - embodied by the slogan that they were acting now as if they were where they could be in two weeks - is just as important when facing Omicron. Cases are doubling every four to six days (much faster than the nine day doubling rate we saw in 2020). But these numbers are telling us about the state of the outbreak at least a week ago, not where we are today.
Today's case numbers reflect the tests processed yesterday, from samples taken a day or two before that, from people infected as much as a week before that. More than 100 people may have been infected with Omicron last Sunday alone, when the Prime Minister announced the discovery of community transmission.
The official case count for that day was just 24.