Defending world champion Shawn Barber of Canada finished eighth.
Pre-race favourite Wayde van Niekerk dominated the one-lap sprint in London, easing up at the line and still winning by almost half a second, in 43.98, over Bahamian Steven Gardiner.
"It was clearly explained to the teams in writing on Sunday and in person to the Botswanan delegation, a member of which was present with many other representatives of teams at a meeting that took place at the Guoman Tower Hotel on Sunday".
Irish Athletics have now confirmed their decision that all athletes coming into the team headquarters for the remaining events of the championship will be housed in a separate hotel. Lane 7 was left empty.
"Then I went out, I just go to do my warm up for the 200".
Behind him, Adam Kszczot of Poland took silver, edging Kipyegon Bett of Kenya.
Trinidad's Jereem Richards ran the fastest time of 20.05.
However last night Dr Pam Venning, the head of medical services for the IAAF, athletics' governing body, insisted that Makwala had come into their medical centre of his own accord on Monday and was seen by one of their volunteer doctors and examined.
On Facebook, he posted he hoped he will be well enough to compete in the 400m finals on Tuesday. "I still maintain I am not sick. I shall rise again". He is the first back-to-back world championship gold medalist since USA's Jeremy Wariner won in 2005 and 2007. I saw Isaac just before the 200m heats, and the only thing I could think of was wrapping my arms around him and telling him he should get well soon.
"Tori Bowie has withdrawn from the 200 meters as she continues to recover from her fall at the conclusion of the women's 100-meter final Sunday evening", the US track federation said in a statement. Her status for the relays Friday and Saturday was to be determined.
"Silver or bronze, it's nearly the same", Lavillenie explained.
Olympic champion Sara Kolak of Croatia was fourth at 64.95.
In addition to breaking Johnson's world record in the 400 in Rio de Janeiro, van Niekerk beat Johnsons' world best in the 300 meters in June with a 30.81-second performance in Ostrava.
The South African's time of 43.98 seconds was nearly a second down on the astonishing record he set a year ago in Rio, but he was still 0.43secs clear of Steven Gardiner in second and the fast-finishing Abdalelah Haroun in third.
Several German and Canadian athletes staying at the Tower Hotel fell ill last week.
The innocent bystander was Van Niekerk, who, truth be told, would've been favored to win this race had Makwala been there anyway. We've seen through nearly every event, this competition is very unpredictable, but I know I've got the ability.
Away from the track, we have the women's javelin final at 19:20 and the men's pole vault final at 19:35.