The majority of western nations have lifted most if not all COVID restrictions, however we are not seeing a massive rise in serious cases of COVID-19.
Why is it different in China? Do they have a different strain?
The majority of western nations have lifted most if not all COVID restrictions, however we are not seeing a massive rise in serious cases of COVID-19.
Why is it different in China? Do they have a different strain?
There are a number of different reasons, all adding up to the current situation.
The strain: There is not a special strain going on in China, according to different references it is mostly the Omicron BF.7 substrain. This strain is highly transmissible (with reported $R_0$ over 10, meaning each infected person infects on average another 10; the Delta strain (which was also already seen as highly infectious) "only" came to an $R_0$ of 5-6). Additionally this strain has accumulated mutations which allow immune escape, a shorter incubation time.
Covid politics: China went from a very strict zero Covid politics to no restrictions at all in the matter of days. Additionally, testing almost completely stopped. This happened with the rise of the highly contagious variant. People started getting together and spread the virus very fast, leading to the current problems.
Vaccinations: In China only the relatively inefficient Sinovac vaccine has been used, as far as I know only two vaccinations are common, with no preference for the older part of the society. How this vaccination (which happened some time ago mostly) will be able to prevent severe disease and death remains to be seen. However, the vaccination status could be better.
Immune status: Curiously, this point is connected to the zero Covid policy. This lead to many people in the Chinese society having never had contact to SARS-COV2. Without this contact, immunity cannot be built (besides vaccinating), this may be an advantage for other societies which had more contact with the virus, although immunity wanes over time.
Population: All the areas where Covid surges now are urban centers with a really high population density. Additionally public transport leads to a lot of potential contacts.
Every of this point attributes a bit to the current problem, but only the combination made it so severe.
References
however we are not seeing a massive rise in serious cases of COVID-19.
Because we've already had a huge Omicron wave in December 2021/January 2022 while China is only reopening today. This means that their population is highly vulnerable to becoming infected with the Omicron variant and they need to go through a massive COVID wave to acquire proper immunity. See the Boston Wastewater data tracking the presence of COVID in the city:
That giant spike in late 2021 is precisely what's going on in China right now. Note that they're in an even worse shape than the US because <1% of their population was infected prior to December 2022 and their vaccine efficacy is lower compared to Pfizer/Moderna's product. They'll go back to having the same baseline of cases as the US once the initial wave subsides and the herd immunity threshold is reached.
1/ China hasn't built up natural herd immunity, only 0.1% has had it.
2/ Restrictions are lifting in winter, the worst time to lift them for a low immunity nation.
3/ Some Chinese populations are frustrated by extreme and unreasonable covid rules, they may not quarantine voluntarily after watching the world cup.
4/ China has administered 3,5 billion doses of a fairly effective vaccine, it reduces mortality by 90+ percent, however they may have administered the second dose too long ago in 2020 and 2021 to be very effective today.
5/ Everyone knows that the government gives false information, they don't know what is true and what isn't.