Why didn’t the increase in cases happen earlier?

[Forky123]

I mean, how come it’s now? How come it wasn’t earlier during that summer, after the lockdowns eased up a bit?

Is it just because this is the way exponential increases work? Just all of a sudden, wham?

Did outdoor socializing play a big part I’m not spreading it?

If it’s spread by kids/schools, how come we didn’t see a sharper increase sooner in September?

It takes a while for growth to happen, and the rate of growth is much lower now than in March. Cases were very very low in late summer.

Schools going back, university students and a change in the weather will have pushed R from just under 1 to 1.1 to 1.5 depending on where you are in the country.

Obviously growth is much slower in London where immunity is higher, compared to places which were relatively unaffected the first time around.

Probably in March - we only saw the late stage and an incomplete picture of that - because testing capacity not high and people encouraged to stay at home without a test if possible. It likely began spreading much earlier than the rises show.

It takes time to spread. Eat out to help out, schools going back, Boris telling everyone to go back to the office, universities-all of them contributed.

Schools, here at least, weren't open to all year groups until the 3rd/4th week of September.

It's seasonal, like all respiratory viruses. Probably doesn't have much to do with restrictions or behaviour.

It takes a while for the growth to take hold. Say the average time from infection to symptoms was a week (I know it is a little less than that but for this example). Patient zero comes back from holiday with CV on 1st September, symptoms appear on 7th Sept and they infect two other people. By 14th those people are now ill (so 3 ill), they have each infected two more people, so 4 incubating who are ill on 21st with 8 incubating. 28th 8 more ill, 16 incubating. 5th October 16 more ill, 32 incubating. 12th October 32 more ill, 64 incubating. 19th Oct 64 more ill, 128 incubating. 26th Oct 128 more ill, 256 incubating.

The rise is small at first but later on the rates increase. Also consider that schools are back, parents who couldn't work due to childcare are back, furlough is winding down. People who were happy to meet at the park or in gardens now meet in the house or in a pub (where permitted)

Better testing
It is only in the past few weeks that mass testing has been available

People have realised that the 3 symptoms touted by the government are not correct and so are testing when they have a headache and sore throat (the prevalent 1st symptoms) and coming back positive.

Ok so I’m not in the UK but I think the numbers have rapidly jumped everywhere generally.

Our schools were back last week of August, so it feels like it took a good month for the cases to really increase, which given the pace of this thing, just felt a bit slower than I would’ve imagined.

How is it seasonal? Does it survive better in colder weather? Or just that people are more likely to speed it indoors? What exactly makes a virus seasonal or not?

How is it seasonal?
Probably a combination of this virus being suited to colder weather, more interactions indoors, and stronger immunity during summer months due to higher vit d levels from sunlight.

It looks like hospitalisations started increasing by August 26. This means infections must have started increased by mid August at the latest. My guess is we all just relaxed after the harsh first lockdown and we saw deaths drop to very low levels.

Very few people had it in June/July, which is why it didn't spread much when things started opening up. If no-one who went to a pub, party, etc had it, then obviously it wouldn't spread. But as it slowly spread, there was more chance of someone attending a pub/party having it and spreading it. That's exponential growth. Think of it like a game of tag. If only one person is "it" in say, a sports field, very little chance of them "tagging" you. But if there's 10 people who are "it", you can't keep away from them all and sooner or latter one of them will get you!

@CovidClara

Better testing It is only in the past few weeks that mass testing has been available

People have realised that the 3 symptoms touted by the government are not correct and so are testing when they have a headache and sore throat (the prevalent 1st symptoms) and coming back positive.

But hospital admissions, ICU bed use and covid deaths have all been rising too since mid-late August, so it's not just about testing capacity.

In march it was only just getting started , like lots if Corona viruses ( common cold, influenza) it ebbs in the warmer weather and is much more prevalent in the winter.
There's no mystery to it.

Exponential growth. Every so many days, cases double. The higher the transmission rate, the less days to double. Before lockdown, it was about every 3 days. It's much slower now, but if you don't stop those little numbers, they become bigger numbers pretty quickly.

1
2
4
8
16 Why are we worrying about this, more chance of getting struck by lightning
32
64
128
256
512
1024 I can't believe people are making this much fuss over such a tiny percentage of the population
2048
4096
8192
16384
32768 - stop me when you think we have a problem
65536
131072 - getting some pretty big jumps here, aren't we?
262144
524288 - maybe we should have done something a bit earlier....
1048576
2097152

People will blame schools but perhaps it's a mixture of things.

Cases were slowly increasing already, remember they stalled the reopening of bowling alleys/soft play etc. They said we were at the limit of what we could open. We've had people going back to workplaces in droves, then schools, colleges and universities.

Perhaps the change of season. People getting complacent with social distancing.

I don't get the seasonal part with CV either because hot countries had mass cases in blazing sunshine.

Flu is seasonal in all temperate countries, but in the tropics people get it all year round. I think it's the same for all respiratory viruses. Nobody knows why

During the summer very few had the virus. Since August people have returned from holidays, gone back to work, are using public transport, are going out again, etc and as more people catch it, it gets transmitted quicker.

I think London had a bigger exposure to the virus during the first wave and probably built up some herd immunity already.

When more and more people started going out, busy (e.g. mall) cafes were no longer cleaning tables between customers. People repeatedly adjust their masks with their hands, and this will transmit coronavirus from hands to the wearer, or via hands to the next person to touch e.g. a lift button etc.

More and more transmission will be by fomites.

On top of this, social distancing has gone to hell and anecdotally restaurants aren't universally sufficently spacing tables. Then closure at 10 began and people are now socialising drunk and uncontrolled in the street. Mask make people feel less need to distance and this only gets worse when drunk. There will be increasing transmission from strangers at a distance of

I don't get the seasonal part with CV either because hot countries had mass cases in blazing sunshine

A lot of very hot countries have a lot of air conditioning. It’s possible that contributed to spread.

I think it was on its way up slowly in August but it really took off when schools went back in Sept and then Universities a bit later than that.
I’m not in Scotland but didn’t the rates start to rise a little earlier in Scotland as the kids go back sooner there?

Cases fell to a very low level in the summer but didn’t completely go away, particularly in some areas where it rumbled on so could easily take off again. I think it was a combination of factors: pubs that opened ignoring distancing measures; people returning to offices; people in bars and nightclubs on holiday in August; visitors from countries with higher cases staying with relatives; people relaxing on indoor gatherings in homes because pubs were open. Here in South London increase seems to be at lower rate possibly due to partial immunity but also less return to normal life than in other areas: lots of offices still closed, fewer people socialising in centre, big places of worship don’t seem to have reopened.

We used to look at daily deaths not positive cases. It’s rising because we are testing more. It would be better to look at deaths to get a comparison with earlier in the year as we didn’t test widely then.

I think allowing travel abroad was crazy over the summer months. We have people bringing new mutations of the virus back into the country which may have sparked new outbreaks.

People relaxed and the government encouraged this by the eat out to help out scheme and telling people to get back into the office. Cases were rising in mid August. There was a halt to opening bowling alleys and soft play. The scientists said it was likely we had reached our limit in opening up. Within two weeks what had happened? Schools,colleges and universities opened, bowling alleys and soft play were open and more nightclubs re licensing as bars (with opening times and social media to suggest they were still actually nightclubs) were opening. No big surprise cases are rising. Obviously as mitigation’s are in place eg mask, limited amount of people meeting so rise is slower at the moment than March but it is only end of Oct. We have at least another 3 months of this to get through. UK needs a reset button and reopen more cautiously and when scientists say we’ve reached the limit listen to them.