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  • Dr. Young Lee

Why the Delta Variant matters & Opening up in the future

Why the Delta Variant matters & Opening up in the future Hi everyone! It’s been a while since my last email. I’ve been watching the Olympic games and honestly felt too lazy to write a newsletter. Anyway - I’ve found some motivation, so here it is! To everyone who is new to this - I send out periodic emails maybe 1-2x/month to update everyone on what’s happening with Covid19, the clinic and some general health news. I usually give my own spin on the interpretation of health information so that it’s more digestible for most lay people. I hope that you find this information useful. COVID19 and the Delta Variant - why this matters COVID19 is a respiratory virus which is highly infectious, and causes more severe illness and death compared with flu or the common cold. It has now been 21 months since the virus was discovered and the world is still in the grips of this pandemic. Viruses will naturally mutate over time. Typically viruses tend to mutate to become more infectious and less deadly - which is a great survival mechanism because the virus gets to live without killing the host. The World Health Organization (WHO) has started classifying significant mutations using the Greek alphabet (i.e. Alpha, Beta, Delta etc) to try to avoid stigmatizing countries (i.e Chinese, Indian, South African variant etc). It’s not a bad idea, given that hate crimes are always a bad thing. We know that words can change how we think about things, so I think this is a smart move. The big problem with the Delta variant is that it’s much more transmissible than the previous variants and it’s basically the majority variant in the world now. Th r0 value is the likely number of people and infected person would spread the virus to, in an unvaccinated, unrestricted movement environment. The original covid19 virus had an r0 value of 2 or so, Alpha has an r0 value of about 4, and Delta about 5-8. That means that the Delta variant is 4x more infectious than the original variant. In terms of it’s virulence (ability to make you sick), it doesn’t seem any weaker than the original. When an infection becomes much more transmissible - there are a whole bunch of problems that happen:

  • 4x more people get sick. There is a lot more hospitalizations and deaths

  • Even with vaccinations - more vaccinated people will get sick because of 2 reasons: 1. There is simply more cases, which means that even if the vaccine is 94% protective against severe illness or death - 6 in 100 people will still get very sick or die. If they are 4x more cases, then you’ll just have 4x more severe illness or death anyway. 2. Variants tend to penetrate the vaccine a bit more. Vaccines still work, but a little less well

  • Herd immunity is super hard to achieve. Herd immunity is the protection that the population has against a virus spreading if enough people are vaccinated. For example, if there are a lot of vaccinated people, the virus has less people to spread to, and will eventually die off. With an r0 value of 2, we probably need about 70% of the population vaccinated to achieve herd immunity. With the Delta variant with and r0 of 5-8, we probably need >90% of the population vaccinated. This is achievable but hard to do - for example in various times in history small pox, polio and measles have had >90% of the population vaccinated. Unfortunately vaccination rates are lower nowadays i.e. in NZ, measles and polio have ~ 84% vaccination rates. Also - we aren’t currently vaccinating people under 18, so that’s ~ 20% of the population who aren’t eligible for vaccinations yet.

  • Vaccinations might require boosters in the future for better protection against variants. The antibodies that your body produces in response to vaccinations start to gradually reduce a bit over time. We don’t really know how quickly - but the original people who were vaccinated during the trials are being followed up and measured.


In short, having a more infections COVID19 means that controlling it or getting rid of it has just gone from difficult, to very difficult to do because we need much more of the population vaccinated. Let me put it this way - when was the last time, in your group of say 100 friends, that 90 of them all agreed on the same thing? Now try that with 7.8 billion people. Or in New Zealand’s case, about 5 million people. It’s not impossible - just really hard. What will probably happen with the vaccine roll out? Due to supply constraints, as New Zealand is only using the Pfizer vaccine - the vaccination program is being done in stages, roughly from oldest to youngest, because older people are more likely to get sick and die. It will probably take till December 2021 to vaccinate all the adults who want to be vaccinated. Medsafe, our medicine safety body - has approved the Pfizer vaccine for people aged 12-18. When supplies are available, I’m pretty sure 12-18 year old’s will be invited to be vaccinated from Jan 2021 onwards. As the safety date for people under 12 is available, it’s likely that we will start vaccinating them as well, probably from early or mid 2022. It’s also quite possible that 1 year after vaccination, we will be asked to have a booster shots for new variants - probably starting with older people. New Zealand and Australia are also very likely to be paying for and giving vaccines to the Pacific Islands. This is a smart move, because ultimately we are all citizens of the world. If they have rampant disease, it wouldn’t be surprising if it ultimately comes to our shores. So it’s not purely altruistic. How will New Zealand probably open up? Well, this is just and educated guess. It’s likely that Covid19 will never be truly eradicated unless countries around the world can convince >90% of their population to get vaccinated. Unfortunately - if you use USA as an example, this is highly unlikely. If you look at the number of people who have received their first shot, and second shot it’s about the same (54% and 53.8%). That means that almost everyone that has wanted a vaccine in USA has gotten one. Usually the spread would be a lot bigger i.e. Canada (71% and 60%). That means that plenty of new people are getting vaccinated and we are just watching them wait 3-4 weeks for their 2nd shot. The likely scenario is that once New Zealand has achieved about 70%+ vaccination rates, we are likely to open green travel corridors with select countries with similar vaccination rates and low rates of Covid19. Presumably this would be with countries such as Australia, China, Singapore, Taiwan, etc. This will probably happen around the middle of next year, i.e. mid 2022. By 2023, most of the world will have some measure of vaccinations. It’s likely that we would have learnt to “live” with covid19. That means that borders are likely to be fully opened and that we just have to accept that a certain number of people will get sick. Covid19 vaccinations will probably be part of the immunization schedule, including childhood vaccinations. Hopefully hospitalizations and deaths will be rare.

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