Wierer and Hermann were both off target in Sunday's sprint with Olympic individual champion Hanna Oeberg taking victory to complete a strong weekend for the Swedish women.
Boe on top, but look out for Laegreid
For Johannes Thingnes Boe, the start of the new campaign did not quite go to plan as Sturla Holm Laegreid pulled off a shock first World Cup win.
In just his fifth IBU World Cup start, the 23-year-old hit all 20 targets out of 20 to beat Boe by 19.4 seconds with Germany's three-time Olympic medallist Erik Lesser third.
Laegreid was one of the later starters but took a clear lead after the third round of shooting and held his nerve to go five for five with his final set.
Boe missed one shot in his opening round, and taking that single penalty loop proved decisive as his inexperienced team-mate triumphed.
Laegreid missed just one target in his four World Cup appearances last season but told the IBU afterwards, "I do not know, It is just luck. I will try to keep up but it is very hard. I think some mistakes will come now and then but hopefully not tomorrow.
"I did not think I would have any chance of winning today. It was so sick to hear my trainers telling me I was in the lead… It was unbelievable."
Laegreid did miss a shot in Sunday's sprint, but it made little difference as he was a long way adrift of runaway winner Boe who at his brilliant best.
Having said he had done "a very good job" on Saturday, the 27-year-old took his tally to 44 World Cup wins with a devastating performance.
Boe made all 10 of his shots and skied faster than anyone to win by 44.1 seconds from Sweden's Olympic relay gold medallist Sebastian Samuelsson who missed one target.
Another Swede, Martin Ponsiluoma, took third.
Afterwards, Boe told IBU, "It was full attack from start to finish. My three loops were quite well skied. I had a good plan for my prone today, to attack more., even though one bullet was really lucky. But I went on and shot clean. That made me really secure for the standing after a good feeling yesterday. To shoot clean and have a win; it is early in the season, but I like it.
"It is very important; important for the self-confidence to get wins. I am very satisfied and see some things that I can do for the next races." - Johannes Thingnes Boe
Thrilling start to women's biathlon season
Clean shooting also made the difference in Saturday's night-time women's opener, the 15km individual, as reigning world champion Dorothea Wierer edged out Germany's Denise Herrmann by just 0.8s.
Sweden's Johanna Skottheim was third with her team-mate and Olympic champion Hanna Oeberg seventh after missing two targets.
Wierer, who told Olympic Channel she was "never ready" for a new season, slowed in the closing stages having led by over 30 seconds after the final shoot.
And despite Hermann - who won an Olympic medal in cross-country skiing before switching to biathlon - charging home, the Italian just held on for her ninth World Cup win.
Wierer had a warning for her rivals afterwards, saying, "I am not in great shape at the moment, but I hope with more races it comes slowly.
"It is a good feeling to be back on the podium. I was really happy about my shooting today. It was really hard for me on the tracks especially the fourth and last loops."
Oeberg made amends in Sunday's sprint, making all 10 of her shots to win by 23.9 seconds from Norway's Olympic silver medallist Marte Olsbu Roiseland.
It was the first sprint World Cup win for a Swedish woman since Helena Ekholm in February 2011.
Roiseland's team-mate Karoline Knotten was third for her best individual World Cup finish.
But the strength of the Swedish team was perhaps the biggest takeaway from the weekend.
Swedish women filled four of the top seven places in the 15km individual and three of the top five in the sprint.